Add list of maintainers to README.md (#237)

README.md

@@ -2,3 +2,24 @@
 
 * [Protobuf](./protobuf/README.md)
 * [Semantic Convention Generator](./semantic-conventions/README.md)
+
+## Contributing
+
+See [CONTRIBUTING.md](CONTRIBUTING.md)
+
+### Approvers
+
+- OpenTelemetry Specification Approvers ([@open-telemetry/specs-approvers](https://github.com/orgs/open-telemetry/teams/specs-approvers))  
+  - See [open-telemetry/community](https://github.com/open-telemetry/community/blob/main/community-members.md#specifications-and-proto) for the current list.
+
+_Find more about the approver role in [community repository](https://github.com/open-telemetry/community/blob/master/community-membership.md#approver)._
+
+### Maintainers
+
+- OpenTelemetry Technical Committee ([@open-telemetry/technical-committee](https://github.com/orgs/open-telemetry/teams/technical-committee))
+  - See [open-telemetry/community](https://github.com/open-telemetry/community/blob/main/community-members.md#technical-committee) for the current list.
+- OpenTelemetry Semantic Conventions Maintainers ([@open-telemetry/specs-semconv-maintainers](https://github.com/orgs/open-telemetry/teams/specs-semconv-maintainers))  
+  for the [Semantic Convention Generator](./semantic-conventions/README.md) sub-project.
+  - See [open-telemetry/semantic-conventions](https://github.com/open-telemetry/semantic-conventions#contributing) for the current list.
+
+_Find more about the maintainer role in [community repository](https://github.com/open-telemetry/community/blob/master/community-membership.md#maintainer)._