add doc for get step version pinning
* Fly has a new sub-command `pin-resource`. It allows you to pin a resource given a partially matched version. It can also be used to set or update a pin comment. #2702 #4417.
+#### <sub><sup><a name="v560-note-4380" href="#v560-note-4380">:link:</a></sup></sub> feature
+
+* When configuring a job, the `version:` field on a `get` step allows partial version matching for pinning input.
+
#### <sub><sup><a name="v560-note-4481" href="#v560-note-4481">:link:</a></sup></sub> feature
* @evanchaoli added `age` column to `fly workers`, #4481.
