Added "pingme" module and corrected the syntax for @load/@unload in the README.md.

On request, sends private messages to users when there is activity in a quiet room. I have the inactivity period set to 30 minutes now (1800 seconds) now, but it can be set
to a few seconds for testing.  (The inactivity period has not been added to the setup file yet.)  "Activity" means messages, not join/leave notifications.

Use the following commands:

@rememberme - add yourself to the ping list
@forgetme   - remove yourself from the ping list
@wipeall    - remove everyone from the ping list
@pinglist   - lists all people who have signed up to be pinged
@pingmehelp - print this list.

Also, I corrected the @load / @unload syntax in the README.md.