Stable releases description in Cosmos SDK repo is stale, needs Stargate and maintenance plan

[barriebyron]

Summary of Bug

https://github.com/cosmos/cosmos-sdk/blob/master/STABLE_RELEASES.md needs an update for the stargate release v0.40 and later

Who is the release owner? (someone at REGEN?) Can we get some love for this important file?

Version

Steps to Reproduce

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[amaury1093]

Yes! This task might go hand-in-hand with updating the CONTRIBUTING guide, especially its "Release Procedure" subsection, as there's some overlap in the 2 docs.

Probably @robert-zaremba and I can take care of that, since we're assigned to the v043 QA and release process (#9116)