[docs] Add contribution guidance section in document (apache#2411)

Co-authored-by: gaotingkai <rookiegao712@gmail>

README.md

@@ -128,6 +128,82 @@ The code in this repository is licensed under the [Apache Software License 2](ht
 
 CDC Connectors for Apache Flink<sup>®</sup> welcomes anyone that wants to help out in any way, whether that includes reporting problems, helping with documentation, or contributing code changes to fix bugs, add tests, or implement new features. You can report problems to request features in the [GitHub Issues](https://github.com/ververica/flink-cdc-connectors/issues).
 
+### Code Contribute
+
+1. Left comment under the issue that you want to take
+2. Fork Flink CDC project to your GitHub repositories
+![fork](/_static/fig/contribute_guidance/fork.png "fork")
+3. Clone and compile your Flink CDC project
+```bash
+git clone https://github.com/your_name/flink-cdc-connectors.git
+cd flink-cdc-connectors
+mvn clean install -DskipTests
+```
+4. Check to a new branch and start your work
+```bash
+git checkout -b my_feature
+-- develop and commit
+```
+![check_branch](/_static/fig/contribute_guidance/check_branch.png "check_branch")
+5. Push your branch to your github
+```bash
+git push origin my_feature
+```
+6. Open a PR to https://github.com/ververica/flink-cdc-connectors
+![open_pr](/_static/fig/contribute_guidance/open_pr.png "open_pr")
+
+### Code Style
+
+#### Code Formatting
+
+You need to install the google-java-format plugin. Spotless together with google-java-format is used to format the codes.
+
+It is recommended to automatically format your code by applying the following settings:
+
+1. Go to "Settings" → "Other Settings" → "google-java-format Settings".
+2. Tick the checkbox to enable the plugin.
+3. Change the code style to "Android Open Source Project (AOSP) style".
+4. Go to "Settings" → "Tools" → "Actions on Save".
+5. Under "Formatting Actions", select "Optimize imports" and "Reformat file".
+6. From the "All file types list" next to "Reformat code", select "Java".
+
+For earlier IntelliJ IDEA versions, the step 4 to 7 will be changed as follows.
+
+- 4.Go to "Settings" → "Other Settings" → "Save Actions".
+- 5.Under "General", enable your preferred settings for when to format the code, e.g. "Activate save actions on save".
+- 6.Under "Formatting Actions", select "Optimize imports" and "Reformat file".
+- 7.Under "File Path Inclusions", add an entry for `.*\.java` to avoid formatting other file types.
+Then the whole project could be formatted by command `mvn spotless:apply`.
+
+#### Checkstyle
+
+Checkstyle is used to enforce static coding guidelines.
+
+1. Go to "Settings" → "Tools" → "Checkstyle".
+2. Set "Scan Scope" to "Only Java sources (including tests)".
+3. For "Checkstyle Version" select "8.14".
+4. Under "Configuration File" click the "+" icon to add a new configuration.
+5. Set "Description" to "Flink cdc".
+6. Select "Use a local Checkstyle file" and link it to the file `tools/maven/checkstyle.xml` which is located within your cloned repository.
+7. Select "Store relative to project location" and click "Next".
+8. Configure the property `checkstyle.suppressions.file` with the value `suppressions.xml` and click "Next".
+9. Click "Finish".
+10. Select "Flink cdc" as the only active configuration file and click "Apply".
+
+You can now import the Checkstyle configuration for the Java code formatter.
+
+1. Go to "Settings" → "Editor" → "Code Style" → "Java".
+2. Click the gear icon next to "Scheme" and select "Import Scheme" → "Checkstyle Configuration".
+3. Navigate to and select `tools/maven/checkstyle.xml` located within your cloned repository.
+
+Then you could click "View" → "Tool Windows" → "Checkstyle" and find the "Check Module" button in the opened tool window to validate checkstyle. Or you can use the command `mvn clean compile checkstyle:checkstyle` to validate.
+
+### Documentation Contribute
+
+Flink cdc documentations locates at `docs/content`.
+
+The contribution step is the same as the code contribution. We use markdown as the source code of the document.
+
 ## Community
 
 * [DingTalk](https://www.dingtalk.com/) Chinese User Group

docs/content/about.md

@@ -292,6 +292,82 @@ mvn clean install -DskipTests
 
 The dependencies are now available in your local `.m2` repository.
 
+### Code Contribute
+
+1. Left comment under the issue that you want to take
+2. Fork Flink CDC project to your GitHub repositories
+   ![fork](/_static/fig/contribute_guidance/fork.png "fork")
+3. Clone and compile your Flink CDC project
+```bash
+git clone https://github.com/your_name/flink-cdc-connectors.git
+cd flink-cdc-connectors
+mvn clean install -DskipTests
+```
+4. Check to a new branch and start your work
+```bash
+git checkout -b my_feature
+-- develop and commit
+```
+![check_branch](/_static/fig/contribute_guidance/check_branch.png "check_branch")
+5. Push your branch to your github
+```bash
+git push origin my_feature
+```
+6. Open a PR to https://github.com/ververica/flink-cdc-connectors
+   ![open_pr](/_static/fig/contribute_guidance/open_pr.png "open_pr")
+
+### Code Style
+
+#### Code Formatting
+
+You need to install the google-java-format plugin. Spotless together with google-java-format is used to format the codes.
+
+It is recommended to automatically format your code by applying the following settings:
+
+1. Go to "Settings" → "Other Settings" → "google-java-format Settings".
+2. Tick the checkbox to enable the plugin.
+3. Change the code style to "Android Open Source Project (AOSP) style".
+4. Go to "Settings" → "Tools" → "Actions on Save".
+5. Under "Formatting Actions", select "Optimize imports" and "Reformat file".
+6. From the "All file types list" next to "Reformat code", select "Java".
+
+For earlier IntelliJ IDEA versions, the step 4 to 7 will be changed as follows.
+
+- 4.Go to "Settings" → "Other Settings" → "Save Actions".
+- 5.Under "General", enable your preferred settings for when to format the code, e.g. "Activate save actions on save".
+- 6.Under "Formatting Actions", select "Optimize imports" and "Reformat file".
+- 7.Under "File Path Inclusions", add an entry for `.*\.java` to avoid formatting other file types.
+  Then the whole project could be formatted by command `mvn spotless:apply`.
+
+#### Checkstyle
+
+Checkstyle is used to enforce static coding guidelines.
+
+1. Go to "Settings" → "Tools" → "Checkstyle".
+2. Set "Scan Scope" to "Only Java sources (including tests)".
+3. For "Checkstyle Version" select "8.14".
+4. Under "Configuration File" click the "+" icon to add a new configuration.
+5. Set "Description" to "Flink cdc".
+6. Select "Use a local Checkstyle file" and link it to the file `tools/maven/checkstyle.xml` which is located within your cloned repository.
+7. Select "Store relative to project location" and click "Next".
+8. Configure the property `checkstyle.suppressions.file` with the value `suppressions.xml` and click "Next".
+9. Click "Finish".
+10. Select "Flink cdc" as the only active configuration file and click "Apply".
+
+You can now import the Checkstyle configuration for the Java code formatter.
+
+1. Go to "Settings" → "Editor" → "Code Style" → "Java".
+2. Click the gear icon next to "Scheme" and select "Import Scheme" → "Checkstyle Configuration".
+3. Navigate to and select `tools/maven/checkstyle.xml` located within your cloned repository.
+
+Then you could click "View" → "Tool Windows" → "Checkstyle" and find the "Check Module" button in the opened tool window to validate checkstyle. Or you can use the command `mvn clean compile checkstyle:checkstyle` to validate.
+
+### Documentation Contribute
+
+Flink cdc documentations locates at `docs/content`.
+
+The contribution step is the same as the code contribution. We use markdown as the source code of the document.
+
 ## License
 
 The code in this repository is licensed under the [Apache Software License 2](https://github.com/ververica/flink-cdc-connectors/blob/master/LICENSE).