Update README to indicate we are no longer using Gerrit

Motivation
----------
Update the README so that contributors will no we are no
longer using gerrit and that they will have to sign the
Contributor License Agreement (CLA) when prompted.

Change-Id: Idb88f0eb7f44ecd52d3455481494f11c201ca0a3

Author: jeffrymorris

README.md

@@ -2,7 +2,7 @@ The Official Couchbase .NET SDK
 
 [Chat with us on Discord](https://discord.com/invite/sQ5qbPZuTh) | [Couchbase Forums](https://forums.couchbase.com/c/net-sdk/6)
 
-* master is 3.4 development branch
+* master is 3.9 development branch
 * release27 is 2.7.X development branch
 * release13 is 1.3.X development branch
 
@@ -46,6 +46,6 @@ NOTE: Couchbase Server 5.0+ uses Role-Based Access Control (RBAC) for authentica
 Please checkout this [README](https://github.com/couchbase/couchbase-net-client/blob/master/src/Couchbase.Stellar.CodeGen/README.md) for how to generate the gRPC proxies and stubs for Protostellar.
 
 ## Pull Requests and Submissions ##
-Being an Open Source project, the Couchbase SDK depends upon feedback and submissions from the community. If you feel as if you want to submit a bug fix or a feature, please post a Pull Request. The Pull Request will go through a formal code review process and merged after being +2'd by a Couchbase Engineer. In order to accept a submission, Couchbase requires that all contributors sign the Contributor License Agreement (CLA). You can do this by creating an account in [Gerrit](http://review.couchbase.org), our official Code Review system. After you have created your account, login and check the CLA checkbox.
+Being an Open Source project, the Couchbase SDK depends upon feedback and submissions from the community. If you feel as if you want to submit a bug fix or a feature, please post a Pull Request (PR). The PR will go through a formal code review process and merged after being approved by a Couchbase Engineer. In order to accept a submission, Couchbase requires that all contributors sign the Contributor License Agreement (CLA). When you push a PR, you will be prompted to sign the CLA. 
 
-Once the CLA is signed, a Couchbase engineer will push the pull request to Gerrit and one or more Couchbase engineers will review the submission. If it looks good they will then +2 the changeset and merge it with master. In addition, if the submission needs more work, you will need to amend the Changeset with another Patchset. Note that is strongly encouraged to submit a Unit Test with each submission and also include a description of the submission, what changed and what the result is.
+Once the CLA is signed, you will be able to open the PR and one or more Couchbase engineers will review the submission. If it looks good, they will accept the PR and merge it with master. Note that is strongly encouraged to submit a Unit Test with each submission and also include a description of the submission, what changed and what the result is.