Update advice in CONTRIBUTING.md

CONTRIBUTING.md

@@ -2,9 +2,6 @@
 
 This repository is open to community contributions!
 
-**Development occurs on the `dev` branch, which is merged into `main` on each release.**
-This ensures the examples are in-sync with the latest release.
-
 There are a few options if you'd like to help:
 
 1. File issues for bugs you find or new features you'd like.
@@ -13,6 +10,8 @@ There are a few options if you'd like to help:
 
 Any contributions made are provided under the license(s) listed in this repo at the time of their contribution, and do not require separate attribution.
 
+When you make a PR (other than for purely internal changes), please update the root level `CHANGELOG.md`.
+
 ## Testing
 
 1. Use doc tests aggressively to show how APIs should be used.