[README.md] Enhance formatting and slightly improve wording

README.md

@@ -1,9 +1,11 @@
 # Chum Web Generator
+
 Static website generator to generate a "**Chum Web**" website for [SailfishOS:Chum](https://github.com/sailfishos-chum/), a Sailfish OS community repository.
 
 For an overview of how this project is structured, see [ARCHITECTURE.md](ARCHITECTURE.md).
 
 ## Running
+
 In general, run it as `python -m chumweb`.  It will output the generated website to a subdirectory `www/` of the
 directory specified by the option `out`, i.e. `out/www/` by default (if the option `out` has not been explicitly set).
 
@@ -13,18 +15,36 @@ as an environment variable in the form of `CHUM_OPTION_NAME=value`.
 The full list of options can be found in [chumweb/config.py](chumweb/config.py).
 
 ### Required options
-* Either set:
-  * `obs_user` and `obs_pass` to an user/password combo valid for the SailfishOS-OBS (which this tool uses by default).
-    * Example: `CHUM_OBS_USER=johndoe` and `CHUM_OBS_PASS=hunter2`
-  * `repos` to a list of repos.  (Handy when testing to avoid hitting OBS each time while developing.)
-    * Example: `--repos 4.5.0.24_aarch64,4.5.0.24_i486`
+
+You must set one of the two following options:
+
+* `obs_user` and `obs_pass` to an user/password combo valid for the SailfishOS-OBS (which this tool uses by default).
+
+  Example: `CHUM_OBS_USER=johndoe` and `CHUM_OBS_PASS=hunter2`
+
+* `repos` to a list of repos.  (Handy when testing to avoid hitting OBS each time while developing.)
+
+  Example: `--repos 4.5.0.24_aarch64,4.5.0.24_i486`
 
 ### Other notable options
-* `out=<path>`: change the output directory. Default: `out/`
-* `debug=<bool>`: Enable debug output on the websites, such as package metadata on package sites.  Default: `false`
+
+* `out=<path>`: change the output directory.
+
+  Default value: `out/`
+
+* `debug=<bool>`: Enable debug output on the websites, such as package metadata on package sites.
+
+  Default value: `false`
+
 * `public_url=<str>`: The URL the generated website should be publicly available on.  Used to generate canonical URLs etc.
-* `download_extra_metadata=<bool>`: Whether to download extra metadata from external sites, referenced by OBS metadata.  Default: `true`
-  * This will cause site generation to take longer, so for some development tasks set this to `false`. ☺
+
+* `download_extra_metadata=<bool>`: Whether to download extra metadata from external sites, referenced by OBS metadata.
+
+  Default value: `true`<br />
+
+  The default value causes site generation to take longer, so for some development tasks you may want to set this to `false`. ☺
+
 * `repo_data_dir=<path>`: Directory with `{arch}-primary.xml.gz` files downloaded from an earlier run. 
-  * You can set this to the value of `out/` to avoid downloading the repo each run while developing.
+
+  You can set this to the value of the option `out` (e.g. `out/`) to avoid downloading the repo each run while developing.