Updated README for changes in plugins branch

There's no more pass_words option, so we shouldn't mention that anymore.
Also, commands aren't in a configuration section called "commands"
anymore, so use the new name, ".shell".

README.rst

 -----
 
 1. Copy options.json.tmp to ~/.config/kaylee/options.json and fill the
-   "commands" section of the file with sentences to speak and commands
+   ".shell" section of the file with sentences to speak and commands
    to run.
 2. Run Kaylee with ``./kaylee.py``. This generates a language model and
    dictionary using the `Sphinx Knowledge Base Tool
 -  To run Kaylee with no UI and using a USB microphone recognized as
    device 2: ``./kaylee.py -m 2``
 
--  To have Kaylee pass each word of the matched sentence as a separate
-   argument to the executed command: ``./kaylee.py -p``
-
 -  To run a command when a valid sentence has been detected:
    ``./kaylee.py --valid-sentence-command=/path/to/command``