Add missing code formatting in docs headers

[Tim Graham]

Some docs headers are missing ​backticks for code entities (referred in that sphinx doc as backquotes).

I've attached the start of a patch to give an idea of what to do. I only started the modified files, so please check the rest of those files as well as all other files.

I think we should also remove links (as in docs/topics/performance.txt, for example) from headers as the formatting doesn't look good across all formats and the links should be repeated in the content that follows the header anyway.

While reviewing the headers, it would be a good opportunity to also remove any extra blank lines between sections (we always use 1 blank line between sections) or add any missing blank lines.

If you have any questions, just leave a comment. Thanks!

[Mahendra Yadav]

Hii can you please explain me, I am unable to get what is need to be done.

[Tim Graham]

Did you look at the sample patch? I added a link in the ticket description to the reStructuredText Primer -- maybe that will help. I don't think I can explain the task any more simply.