replace example files with documentation

To not bloat the codebase with unnecessary files, the informations are now in the CONTRIBUTING.md file. This also allow to add some explanations.

Some code refactor is needed to cleanup some things such a the `TRANSLATOR_SERVICES` that should be a configuration value. Some configs should be optional as well. These informations will be updated in the futur.

.github/CONTRIBUTING.md

@@ -99,6 +99,34 @@ To create revisions, you can use [`alembic.sh`](bin/alembic.sh) in the `bin` dir
 
 If you are unfamiliar with alembic, [`here is some information`](/alembic/README). Check also the [documentation](https://alembic.sqlalchemy.org/en/latest/tutorial.html#create-a-migration-script) as well.
 
+## Configuration and environnement
+
+In order to run the bot without any issue, there is some prerequisites.
+
+First, a `.env` file with the following values:
+| Key                   | Requirement | Description |
+|-----------------------|----------|--------------------------------------------------------------------------------|
+| `POSTGRES_USER`       | Required | Used to create the database                                                    |
+| `POSTGRES_PASSWORD`   | Required | Used to create the database                                                    |
+| `POSTGRES_DB`         | Required | Used to create the database                                                    |
+| `MYBOT_TOKEN`         | Required | [Create a bot](https://discord.com/developers/applications) and copy the token |
+| `TOPGG_AUTH`          | Optional | Used to sync top.gg                                                            |
+| `TOPGG_TOKEN`         | Optional | Used to sync top.gg                                                            |
+| `TRANSLATOR_SERVICES` | Optional | Will be deprecated                                                             |
+| `MS_TRANSLATE_KEY`    | Optional | Required if "microsoft" is set in `TRANSLATOR_SERVICES`                          |
+| `MS_TRANSLATE_REGION` | Optional | Required if "microsoft" is set in `TRANSLATOR_SERVICES`                          |
+
+
+Then, create a `config.toml` ([TOML](https://toml.io/en/)) with the following values:
+| Key              | Requirement | Description                                               |
+|------------------|-------------|-----------------------------------------------------------|
+| `SUPPORT_GUILD_ID` | Required    | The bot need to be member and administrator of this guild |
+| `BOT_ID`           | Required    | Used for links and top.gg (if enabled)                    |
+| `BOT_NAME`         | Required    | Used for the webhook logs                                 |
+| `LOG_WEBHOOK_URL`  | Optional    | Used to send bot logs using a webhook                     |
+| `OWNER_IDS`        | Required    | Grant permissions such a eval, extensions reload...       |
+
+
 ## Translations contributions
 
 MyBot is a multi-language bot! The codebase is in English, which is then translated in several languages.