docs: change page title based on current page
docs: change page title based on current page

Closes #4433
progrium/dokku,dokku/dokku,dokku/dokku,claytonbrown/dokku,progrium/dokku,progrium/dokku,progrium/dokku,progrium/dokku,dokku/dokku,progrium/dokku,claytonbrown/dokku,dokku/dokku,claytonbrown/dokku,progrium/dokku,dokku/dokku,claytonbrown/dokku,claytonbrown/dokku,claytonbrown/dokku,claytonbrown/dokku,dokku/dokku,progrium/dokku,claytonbrown/dokku,dokku/dokku,dokku/dokku