Update IG charter, approaches, and grouping spec#6

Open

chughtapan wants to merge 6 commits intomodelcontextprotocol:mainfrom

chughtapan:groups/spec

Commits on Feb 25, 2026

Add grouping extension specification and license
chughtapan
committed

Commits on Mar 4, 2026

Address PR review feedback on approaches doc

chughtapan
and
claude
committed