PRESUBMIT.cfg: use human readable name

BUG=None
TEST=`repo upload` looks nicer

Change-Id: I11134dd887be728048a1095f201cdfdf1f13f794
diff --git a/PRESUBMIT.cfg b/PRESUBMIT.cfg
index 97fce11..7d87bd1 100644
--- a/PRESUBMIT.cfg
+++ b/PRESUBMIT.cfg
@@ -1,2 +1,2 @@
 [Hook Scripts]
-hook0: ./bin/run_tests
+run_tests = ./bin/run_tests