Fix whitespace that caused short-format in generated YAML

If the markdown contains trailing spaces, or has tabs included,
the YAML generator uses a compact format for the text (using `\n`
and `\t`, instead of plain newlines).

The compact format makes it difficult to review changes in the
yaml docs when vendoring in the documentation repository.

This patch:

- removes trailing whitespace
- replaces tabs for spaces
- fixes some minor formatting and markdown issues

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

docs/reference/commandline/network_ls.md

@@ -192,7 +192,7 @@ The following filter matches all user defined networks:
 ```bash
 $ docker network ls --filter type=custom
 NETWORK ID          NAME                DRIVER       SCOPE
-95e74588f40d        foo                 bridge       local  
+95e74588f40d        foo                 bridge       local
 63d1ff1f77b0        dev                 bridge       local
 ```