docs: add WG chairperson responsibilities

[smoya]

Description

This PR expands info about the roles of the WG chairperson(s), how they are elected, and some other helpful info

Completely open to discuss and work together to get the right stuff here.

[smoya]

Pinging current Working Groups chairpersons so you all review this @alequetzalli @jonaslagoni @amzani @thulieblack

[thulieblack]

Looks okay to me

[smoya]

/rtm