Add sr(serbian) docs skeleton.

Fixes #1046
Typo
Merge pull request #1047 from kamui545/patch-1

Typo
Add skeleton for sr(serbian) translation.
Update index.rst
Update contents.rst
Merge pull request #1048 from MihaiTL/patch-5

Update index.rst
Update romanian index line length
Merge pull request #1049 from MihaiTL/patch-6

Update contents.rst