Add new pages for Totem help.
Minor fixup to navigation.page
Split sound page into language and volume
Update help page on zooming and aspect ratio
Fix link to figure in help Makefile.am
Fix help links to sound page
Review file-open.page

Update for UI changes, update wording.
Final review of introduction.page

Add revision tag, update Totem to Videos, slight rewording.
Final review of keyboard-shortcuts.page

Use more descriptive description, mark as candidate for finished help.
docs: added totem icon to the help, and modified index.page and Makefile.am to include it