WIP: Standardize language around X + MAU

Why is this change being made?

The number of product metric terms is increasing. Many have unique acronyms that are becoming hard to keep track of and challenge our habit of to "not use acronyms when you can avoid them".

Since many metrics touch on monthly active users, I propose we standardize on X + MAU, where X is a term that defines the specific MAU that we're referring to. These terms are clearer and easier to pronounce:

Before	Proposed
SMAU	Stage MAU
GMAU	Group MAU
SMAPU	Paid Stage MAU
GMAPU	Paid Group MAU
SOSMAU	Total Stage MAU

Author Checklist

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