update: Added update methods

* Added update methods for bot and plugin_manager. These shall be called
  from the 'update' loop that normally gets executed every 30 seconds.

Signed-off-by: mr.Shu <mr@shu.io>
update: Updated help command

* Updated help command to actually use the docstrings of functions. Only
  the first line of them is taken at this time.

Signed-off-by: mr.Shu <mr@shu.io>