Updated Release Notes (markdown)
added release notes for v0.8.2
added v0.7.3 release notes
added release notes for v0.7.2
added release notes for v0.7.1
added release notes for v0.7.0
added release notes for v0.6.13
added release notes for v0.6.12
Updated Documentation (markdown)
#38357 Moves deprecated Hiero engine docs here.
added release notes for v0.6.6