DAOS-18787 doc: add upgrading.md - #18895

DAOS-18787 doc: add upgrading.md#18895

Michael-Hennecke wants to merge 4 commits into

release/2.8daos-stack/daos:release/2.8from

michael-hennecke/2.8/DAOS-18787-upgradingdaos-stack/daos:michael-hennecke/2.8/DAOS-18787-upgradingCopy head branch name to clipboard