chore: update metadata.yaml for v0.5.0

When doing the v0.5.0 release i failed to update the metadata.yaml. Also
i have added a note to to the release guide to remind me next
time....sigh.

Signed-off-by: Richard Case <richard@weave.works>

Author: richardcase

docs/releasing.md

@@ -1,5 +1,7 @@
 # Releasing CAPMVM
 
+> IMPORTANT - before doing a release that updates the major or minor version make sure you have updated and commited [metadata.yaml](https://github.com/weaveworks/cluster-api-provider-microvm/blob/main/metadata.yaml) with the new version.
+
 ## Determine release version
 
 The projects follows [semantic versioning](https://semver.org/#semantic-versioning-200)

metadata.yaml

@@ -17,3 +17,6 @@ releaseSeries:
   - major: 0
     minor: 4
     contract: v1beta1
+  - major: 0
+    minor: 5
+    contract: v1beta1