Change network.protocol.name from opt-in to conditionally required

Author: trask

CHANGELOG.md

@@ -48,6 +48,8 @@ release.
   ([#459](https://github.com/open-telemetry/semantic-conventions/pull/459))
 - Make `client.address` sampling relevant on HTTP server spans.
   ([#469](https://github.com/open-telemetry/semantic-conventions/pull/469))
+- Change `network.protocol.name` from opt-in to conditionally required.
+  ([#999](https://github.com/open-telemetry/semantic-conventions/pull/999))
 
 ### Features