Add a link explaining AOSP import order.

Bug: 70801907
Test: None
Change-Id: Icb78b4e207f9451ab4f7ba681018ec09892c48e4
diff --git a/default-treewalker-checks.xml b/default-treewalker-checks.xml
index 31c5457..8ae9f56 100644
--- a/default-treewalker-checks.xml
+++ b/default-treewalker-checks.xml
@@ -157,7 +157,7 @@
 </module>
 <module name="ImportOrder">
   <property name="severity" value="error"/>
-  <message key="import.ordering" value="Wrong order for {0} import. Use Ctrl+Shift+O (Eclipse) or Ctrl+Alt+O (Intellij) to sort imports"/>
+  <message key="import.ordering" value="Wrong order for {0} import. Use Ctrl+Shift+O (Eclipse) or Ctrl+Alt+O (Intellij) to sort imports. https://source.android.com/setup/code-style#order-import-statements"/>
   <property name="groups" value="android, com.android, dalvik, com, gov, junit, libcore, net, org, java, javax"/>
   <property name="ordered" value="true"/>
   <property name="option" value="top"/>