Update RELEASING.md (open-telemetry#1843)

RELEASING.md

@@ -75,6 +75,13 @@ After releasing verify that examples build outside of the repository.
 The script copies examples into a different directory removes any `replace` declarations in `go.mod` and builds them.
 This ensures they build with the published release, not the local copy.
 
-## Contrib Repository
+## Post-Release
+
+### Contrib Repository
 
 Once verified be sure to [make a release for the `contrib` repository](https://github.com/open-telemetry/opentelemetry-go-contrib/blob/main/RELEASING.md) that uses this release.
+
+### Website Documentation
+
+Update [the documentation](./website_docs) for [the OpenTelemetry website](https://opentelemetry.io/docs/go/).
+Importantly, bump any package versions referenced to be the latest one you just released and ensure all code examples still compile and are accurate.