[Doc] Add links to client docs and feature matrix in README.md (apach…

…e#1014)

### Motivation

The new [client feature matrix](https://pulsar.apache.org/client-feature-matrix/) page has been live, so this PR makes the required updates on the doc side.

### Modifications

Add a paragraph to notify both users and contributors about the new client feature matrix.

README.md

@@ -18,21 +18,23 @@
     under the License.
 
 -->
+
 [![PkgGoDev](https://pkg.go.dev/badge/github.com/apache/pulsar-client-go)](https://pkg.go.dev/github.com/apache/pulsar-client-go)
 [![Go Report Card](https://goreportcard.com/badge/github.com/apache/pulsar-client-go)](https://goreportcard.com/report/github.com/apache/pulsar-client-go)
 [![Language](https://img.shields.io/badge/Language-Go-blue.svg)](https://golang.org/)
 [![LICENSE](https://img.shields.io/hexpm/l/pulsar.svg)](https://github.com/apache/pulsar-client-go/blob/master/LICENSE)
+
 # Apache Pulsar Go Client Library
 
-A Go client library for [Apache Pulsar](https://pulsar.apache.org/).
+A Go client library for [Apache Pulsar](https://pulsar.apache.org/). For the supported Pulsar features, see [Client Feature Matrix](https://pulsar.apache.org/client-feature-matrix/).
 
 ## Purpose
 
 This project is a pure-Go client library for Pulsar that does not
 depend on the C++ Pulsar library.
 
 Once feature parity and stability are reached, this will supersede the current
-CGo based library.
+CGo-based library.
 
 ## Requirements
 
@@ -156,12 +158,14 @@ Run the tests with specific versions of GOLANG and PULSAR:
 
 Contributions are welcomed and greatly appreciated. See [CONTRIBUTING.md](CONTRIBUTING.md) for details on submitting patches and the contribution workflow.
 
+If your contribution adds Pulsar features for Go clients, you need to update both the [Pulsar docs](https://pulsar.apache.org/docs/client-libraries/) and the [Client Feature Matrix](https://pulsar.apache.org/client-feature-matrix/). See [Contribution Guide](https://pulsar.apache.org/contribute/site-intro/#pages) for more details.
+
 ## Community
 
 ##### Mailing lists
 
 | Name                                                      | Scope                           |                                                       |                                                           |                                                                    |
-|:----------------------------------------------------------|:--------------------------------|:------------------------------------------------------|:----------------------------------------------------------|:-------------------------------------------------------------------|
+| :-------------------------------------------------------- | :------------------------------ | :---------------------------------------------------- | :-------------------------------------------------------- | :----------------------------------------------------------------- |
 | [[email protected]](mailto:[email protected]) | User-related discussions        | [Subscribe](mailto:[email protected]) | [Unsubscribe](mailto:[email protected]) | [Archives](http://mail-archives.apache.org/mod_mbox/pulsar-users/) |
 | [[email protected]](mailto:[email protected])     | Development-related discussions | [Subscribe](mailto:[email protected])   | [Unsubscribe](mailto:[email protected])   | [Archives](http://mail-archives.apache.org/mod_mbox/pulsar-dev/)   |
 
@@ -179,13 +183,13 @@ Licensed under the Apache License, Version 2.0: http://www.apache.org/licenses/L
 
 ### Go module 'ambiguous import' error
 
-If you've upgraded from a previous version of this library, you may run into an 'ambigous import' error when building.
+If you've upgraded from a previous version of this library, you may run into an 'ambiguous import' error when building.
 
 ```
 github.com/apache/pulsar-client-go/oauth2: ambiguous import: found package github.com/apache/pulsar-client-go/oauth2 in multiple modules
 ```
 
-The fix for this is to make sure you don't have any references in your `go.mod` file to the old oauth2 module path.  So remove any lines
+The fix for this is to make sure you don't have any references in your `go.mod` file to the old oauth2 module path. So remove any lines
 similar to the following, and then run `go mod tidy`.
 
 ```