Update RelNotes for 1.5.4 to reflect change in git-status output.

index a4a2a7f..70d1d6c 100644
@@ -86,6 +86,10 @@ Updates since v1.5.3
    to allow checking out a path outside the current directory
    without cd'ing up.
 
+ * "git status" from a subdirectory now shows relative paths
+   which makes copy-and-pasting for git-checkout/git-add/git-rm
+   easier.
+
  * Output processing for '--pretty=format:<user format>' has
    been optimized.