[main] RHIDP-6584 - Document how users can install and configure plugins from Marketplace in RHDH#1161

Gerry-Forde merged 12 commits intoredhat-developer:mainredhat-developer/red-hat-developers-documentation-rhdh:mainfrom

openshift-cherrypick-robot:cherry-pick-1084-to-mainopenshift-cherrypick-robot/red-hat-developers-documentation-rhdh:cherry-pick-1084-to-mainCopy head branch name to clipboard