doc/radosgw: Fix capitalization, tab use, punctuation in two files

doc/radosgw: Fix capitalization, tab use, punctuation in two files

Use title case consistently in section titles.

Capitalize first letter for Ceph, Unix, Luminous.

Capitalize RGW and NFS-Ganesha consistently.

Remove a colon from end of a section title in nfs.rst.

Add full stops at end of two sentences in sync-modules.rst.

Change tabs into four spaces in nfs.rst.
Also use comments more sensibly in logging example in nfs.rst:
- Indent the comments consistently, fixing a leading space in the
  beginning of the rendered preformatted block.
- Also comment out the closing brace.

Signed-off-by: Ville Ojamo <14869000+bluikko@users.noreply.github.com>