[release-notes] Release notes 7.15.0 on 7.15 branch (#5994)

Co-authored-by: Mpdreamz <Mpdreamz@users.noreply.github.com>

Author: github-actions[bot]

docs/release-notes/release-notes-7.15.0-generated.asciidoc

@@ -1,4 +1,10 @@
 
+[float]
+[[uncategorized]]
+=== Uncategorized
+
+- * Support PIT, Fields and RuntimeFields on AsyncSearch https://github.com/elastic/elasticsearch-net/pull/5989[#5989]  (issue: https://github.com/elastic/elasticsearch-net/issues/5988[#5988])
+
 [float]
 [[bug]]
 === Bug Fixes