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

Automatically pings 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.

Everyone on the "ping list" will get a message when anyone posts a message in a
room that has been quiet for the time period specified in the module.  (The
inactivity period has not been added to the setup file yet.)

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.