3176 Em dashes to colons in people search name help

https://code.google.com/p/otwarchive/issues/detail?id=3176

From issue: 
>1. http://test.archiveofourown.org/help/people-search-name-help.html It looks okay when loaded from the ? on the people search page, but going directly to the URL shows  â€” in place of the em dash. Can we use a colon instead of an em dash? That's what the other help files seem to use.
2. http://test.ao3.org/help/people-search-text-help.html Looks okay, but I think we can actually delete this, since there's not a text field on the people search page anymore.

The bookmarks help can also go bye-bye, since we took that out in https://github.com/otwcode/otwarchive/commit/51dd31651ce561374cb87764a92303b9fd261826