[snmp] add release note

releasenotes/notes/snmp-add-scale-factor-08982b524f340644.yaml

@@ -0,0 +1,11 @@
+# Each section from every release note are combined when the
+# CHANGELOG.rst is rendered. So the text needs to be worded so that
+# it does not depend on any information only available in another
+# section. This may mean repeating some details, but each section
+# must be readable independently of the other.
+#
+# Each section note must be formatted as reStructuredText.
+---
+features:
+  - |
+    [snmp] add scale factor option to metric configurations