Document that online help slows page loads

git-svn-id: https://repo.thevirtualbrain.org/svn/tvb/trunk/tvb_documentation@6370 1c0e02f0-7929-43c0-8fb3-3293bf43b0d1
Fixed a rst typo and some warnings

git-svn-id: https://repo.thevirtualbrain.org/svn/tvb/trunk/tvb_documentation@6371 1c0e02f0-7929-43c0-8fb3-3293bf43b0d1