Enhance README.md

1. Unify punctuation: All full sentences end in an full stop, non-sentences usually not.
2. Enhance legibility when editing by using a double-spaces after full stops not ending a line, plus adding concluding empty line.  Side note: This does not affect the generated HTML code.
3. Rectify two typos.
4. Denote the default value for the option `download_extra_metadata` being `true`.
5. Denote the alternative value for the option `download_extra_metadata` as `false`, because the original text could be read as it being `off`.
6. End all example values for paths with a slash ("/").

README.md

@@ -1,29 +1,30 @@
 # Chum Web
 Static website generator to generate a 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)
+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 "out/www/",
-unless another `out` directory has been specified.
+In general, run it as `python -m chumweb`.  It will output the generated website to `out/www/`,
+unless another directory has been specified by the option `out`.
 
 Options can be specified on the command line in the form of `--option-name value` or
 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)
+The full list of options can be found in [chumweb/config.py](chumweb/config.py).
 
-### Required options:
+### Required options
 * Either set:
-  * `obs_user` and `obs_pass` to an user/password combo that works on SaiflishOS's OBS (which this tool uses by default)
+  * `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)
+  * `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.
-* `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. 
-  * This will cause site generation to take longer, so for some development tasks keep this off :)
-* `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
+* `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`
+* `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`. ☺
+* `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.
+