Rebuild search index in admin options (#647)

Signed-off-by: Thomas Miceli <tho.miceli@gmail.com>

internal/i18n/locales/en-US.yml

@@ -292,7 +292,7 @@ admin.actions.sync-db: Synchronize gists from database
 admin.actions.git-gc: Garbage collect all git repositories
 admin.actions.sync-previews: Synchronize all gists previews
 admin.actions.reset-hooks: Reset Git server hooks for all repositories
-admin.actions.index-gists: Index all gists
+admin.actions.index-gists: Rebuild search index
 admin.actions.sync-gist-languages: Synchronize all gists languages
 admin.id: ID
 admin.user: User
@@ -338,7 +338,7 @@ flash.admin.sync-db: Syncing repositories from database...
 flash.admin.git-gc: Garbage collecting repositories...
 flash.admin.sync-previews: Syncing Gist previews...
 flash.admin.reset-hooks: Resetting Git server hooks for all repositories...
-flash.admin.index-gists: Indexing all gists...
+flash.admin.index-gists: Rebuilding search index...
 flash.admin.sync-gist-languages: Syncing Gist languages...
 
 flash.auth.username-exists: Username already exists