Current.xml and friends are now .txt instead.

(and much much easier to read)

Change-Id: I31832069d4fd78a937802aa20d0b0861bf99768c
diff --git a/core/apicheck_msg_current.txt b/core/apicheck_msg_current.txt
index 5d3a913..440e7f8 100644
--- a/core/apicheck_msg_current.txt
+++ b/core/apicheck_msg_current.txt
@@ -6,10 +6,10 @@
    1) You can add "@hide" javadoc comments to the methods, etc. listed in the
       errors above.
 
-   2) You can update current.xml by executing the following command:
+   2) You can update current.txt by executing the following command:
          make update-api
 
-      To submit the revised current.xml to the main Android repository,
+      To submit the revised current.txt to the main Android repository,
       you will need approval.
 ******************************