Update README (#1294)

README.md

@@ -45,25 +45,24 @@
 ---
 
 # OpenTelemetry Collector Contrib
+
 This is a repository for OpenTelemetry Collector contributions that are not part of the
 [core repository](https://github.com/open-telemetry/opentelemetry-collector) and
 core distribution of the Collector. Typically, these contributions are vendor
 specific receivers/exporters and/or components that are only
 useful to a relatively small number of users.
 
+Please note that this repository and its releases are a superset of the core repository.
+
 ## Creating your own OpenTelemetry Collector distribution
 
-A guide on how to create your own distribution is available in this blog post: 
+A guide on how to create your own distribution is available in this blog post:
 ["Building your own OpenTelemetry Collector distribution"](https://medium.com/p/42337e994b63)
 
-If you are building your own distribution, the [OpenTelemetry Collector Builder](https://github.com/observatorium/opentelemetry-collector-builder) 
+If you are building your own distribution, the [OpenTelemetry Collector
+Builder](https://github.com/observatorium/opentelemetry-collector-builder)
 might be a good starting point.
 
-## Questions
-Reach the Collector community on
-[gitter](https://gitter.im/open-telemetry/opentelemetry-service) if you have
-further questions.
-
 ## Contributing
 
 See [CONTRIBUTING.md](CONTRIBUTING.md).
@@ -134,3 +133,11 @@ Learn more about roles in the [community repository](https://github.com/open-tel
 | Processor                      | Reviewer(s)               |
 | ------------------------------ | ------------------------- |
 | routing                        | @jpkrohling               |
+
+### Extensions
+
+| Extension                      | Reviewer(s)               |
+| ------------------------------ | ------------------------- |
+| httpforwarder                  | @asuresh4                 |
+| jmxmetrics                     | @rmfitzpatrick            |
+| observer                       | @asuresh4 @jrcamp         |