The migration should only create or drop the extensions if necessary.
Altered page to include note about difference between Rails 3 and 4 regarding the schema format.
tsvector_update_trigger returns a trigger which must be used directly in a create trigger sql statement. Since hair_trigger wraps the trigger code in it's own function this doesn't work. A custom tsv update trigger can be used however, the simplest of which I believe is the one now listed here. For more information: http://stackoverflow.com/questions/21147893/tsvector-update-trigger-cant-find-tsvector-column/21156826#21156826 . Also clarify what exactly you're adding the index to.
Change 'you need enough columns for the index to be used' to 'rows'
Updated Building indexes (markdown)
Added `new.tsv := ` in the manual trigger
Improve the wiki page to make it more inviting
Add instructions for Rails
Updated Home (markdown)
Write a rough stub article. It needs work!
Point to the (currently) only wiki page and the Readme.
Copy-pasting @nertzy's answer: https://github.com/Casecommons/pg_search/issues/38#issuecomment-5805148