add release-notes for valid identifiers
concourse/concourse#5810
* Added recover for panic error that used to crash the cluster. Now it should be less easy to panic (we hope!) and if it does, panic error could be found on Stderr and log. #5842
+#### <sub><sup><a name="5810" href="#5810">:link:</a></sup></sub> feature
+
+* Reduce the allowed character set for Concourse valid identifiers. Only prints warnings instead of errors as a first step. #5810
