changelog entry for --all opttion to octodns-validate

CHANGELOG.md

@@ -4,6 +4,9 @@
   Some problem at filename.yaml, line 42, column 14. Our custom Yaml Loaders
   attach this context information, arbitrary string. Other providers may do so
   by creating ContextDict to pass as `data` into Record.new.
+* Add --all option to octodns-validate to enable showing all record validation
+  errors (as warnings) rather than exiting on the first. Exit code is non-zero
+  when there are any validation errors.
 
 ## v1.0.0 - 2023-07-30 - The One