IntelliJ-with-Bazel: Refer users to public website, not github project.

The github repo is just a code drop, and currently not updated. The website contains more up-to-date instructions, in line with the plugin version published to IntelliJ's plugin repo.

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MOS_MIGRATED_REVID=132590585
diff --git a/site/contributing.md b/site/contributing.md
index f5e72c5..4e84abe 100644
--- a/site/contributing.md
+++ b/site/contributing.md
@@ -55,12 +55,8 @@
 
 ### Creating an IntelliJ project
 
-To work with IntelliJ:
-
-* Install the [IntelliJ-with-Bazel](https://github.com/bazelbuild/intellij)
-  plugin.
-* Follow the instructions at [ij.bazel.io](https://ij.bazel.io) to setup your
-  project.
+To work with IntelliJ, follow the instructions at
+[ij.bazel.io](https://ij.bazel.io).
 
 ### Creating an Eclipse project