Changed 'popular choices' to 'your subreddits'

Populating a list of the subreddits you subscribe to does not make them
popular. If a user is subscribed to no subreddits, the suggestion pane
will be populated with nothing.
I think the string should be changed to your_subreddits, until at some
point there is an effort to fill the list with heavily frequented
subreddits in the event that the user has no subreddits of his/her own
to chose form