Add documentation link to deprecated GYP warning

BUG=585553

Review URL: https://codereview.chromium.org/1707533003

Cr-Commit-Position: refs/heads/master@{#377339}
diff --git a/PRESUBMIT.py b/PRESUBMIT.py
index 223f1545..10f7ac06 100644
--- a/PRESUBMIT.py
+++ b/PRESUBMIT.py
@@ -1561,7 +1561,9 @@
   return [output_api.PresubmitError(
       "Found new compiled_resources.gyp files:\n%s\n\n"
       "compiled_resources.gyp files are deprecated,\n"
-      "please use compiled_resources2.gyp instead" %
+      "please use compiled_resources2.gyp instead:\n"
+      "https://chromium.googlesource.com/chromium/src/+/master/docs/closure_compilation.md"
+      %
       "\n".join(added_compiled_resources))]