Docs: add how to get the code and submit changes

Change-Id: Ic6edff3f3924094d10390ed79c195fc8d3e254c7
diff --git a/docs/contributing.md b/docs/contributing.md
index 913d318..53fe1b0 100644
--- a/docs/contributing.md
+++ b/docs/contributing.md
@@ -56,6 +56,7 @@
 - [Set up the development environment](developers/set_up.md)
 - [Build the extension](developers/build.md)
 - [Add a new feature](developers/add_feature.md)
+- [Submit changes for review](https://gerrit.avm99963.com/Documentation/intro-gerrit-walkthrough-github.html)
 - [How to test translations](https://developer.chrome.com/docs/extensions/reference/i18n/#how-to-set-your-browsers-locale)
 
 *** promo
diff --git a/docs/developers/set_up.md b/docs/developers/set_up.md
index 8106933..a8e75ee 100644
--- a/docs/developers/set_up.md
+++ b/docs/developers/set_up.md
@@ -7,6 +7,11 @@
    - This is because the build script uses a Go program to generate the
    manifest.
 1. [Install NPM](https://docs.npmjs.com/downloading-and-installing-node-js-and-npm/).
+1. Now, you must clone the git repository to your device to retrieve the
+extension source code. To do that,
+[go here](https://gerrit.avm99963.com/admin/repos/infinitegforums) and execute
+the "clone with commit-msg hook" command listed there (if you sign in you'll see
+several options: cloning via anonymous HTTP, HTTP, or SSH).
 1. That's it! If you're using a Mac, you're out of luck, because you must
 perform some more steps.