README: Remove the note about the GitHub mirror as there is none

Change-Id: I857820438939beea56fa60f3beb045039c765a82
diff --git a/README.md b/README.md
index 10198de..105e51a 100644
--- a/README.md
+++ b/README.md
@@ -120,8 +120,6 @@
 Please read the [contribution
 guidelines](https://gerrit.googlesource.com/apps/reviewit/+/master/CONTRIBUTING).
 
-Note that we do not accept Pull Requests via the Github mirror.
-
 ## Build-time dependencies
 
 The app uses the following build-time dependencies provided under the given licenses: