Fixed #14767 -- Reflowed paragraphs and cleaned up some markup/links in the...

Fixed #14767 -- Reflowed paragraphs and cleaned up some markup/links in the topics/db/optimizations docs. Thanks to adamv for the report and patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@14690 bcc190cf-cafb-0310-a4f2-bffc1f526a37