Add missing release notes for 6.0.9

documentation/sphinx/source/release-notes.rst

@@ -48,6 +48,7 @@ Fixes
 * Sometimes a minority of coordinators would fail to converge after a new leader was elected. [6.0.6] `(PR #700) <https://github.com/apple/foundationdb/pull/700>`_
 * Calling status too many times in a 5 second interval caused the cluster controller to pause for a few seconds. [6.0.7] `(PR #711) <https://github.com/apple/foundationdb/pull/711>`_
 * Configuring from usable_regions=2 to usable_regions=1 on a cluster with a large number of processes would prevent data distribution from completing. [6.0.8] `(PR #721) <https://github.com/apple/foundationdb/pull/721>`_
+* TLS certificate reloading could cause TLS connections to drop until process restart [6.0.9] `(PR #717) <https://github.com/apple/foundationdb/pull/717>`_
 
 Status
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