Move configuration to separate section to make it easier to discover.

Change-Id: I70ef83de107388e732f3e2eda16511b663ac57ab
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/230959
Reviewed-by: Slava Egorov <[email protected]>
Commit-Queue: Polina Cherkasova <[email protected]>

Author: polina-c

CONTRIBUTING.md

@@ -20,9 +20,13 @@ Before we can use your code, you must sign the [Google Individual Contributor Li
 
 Before you start working on a larger contribution, you should get in touch with us first through the  [Dart Issue Tracker](https://dartbug.com) with your idea so that we can help out and possibly guide you. Coordinating up front makes it much easier to avoid frustration later on.
 
-All submissions, including submissions by project members, require review.  We use the same code-review tools and process as the chromium project.  In order to submit a patch, you need to get the [depot\_tools](http://dev.chromium.org/developers/how-tos/depottools).
+All submissions, including submissions by project members, require review.  We use the same code-review tools and process as the chromium project.
 
-We occasionally take pull requests, e.g., for comment changes, but the main flow is to use the Rietveld review system as explained below.
+We occasionally take pull requests, e.g., for comment changes, but the main flow is to use the Gerrit review system as explained below.
+
+## Setting up Environment
+
+In order to submit a patch, you need to get the [depot\_tools](http://dev.chromium.org/developers/how-tos/depottools).
 
 ## Getting the code
 
@@ -69,7 +73,9 @@ Upload the patch for review:
 git cl upload -s
 ```
 
-The above command returns a URL for the review. Attach this review to your issue in https://dartbug.com
+The above command returns a URL for the review. Attach this review to your issue in https://dartbug.com.
+
+To update the cl, just commit your changes and run `git cl upload -s` for your branch.
 
 If you have commit access, when the review is done and the patch is good to go, submit the patch on https://dart-review.googlesource.com: