Fix RST formatting errors

Clean up some shocco RST errors

Change-Id: I9afa0f155f2bfcc73638ae11447c693579288355
diff --git a/exercises/sec_groups.sh b/exercises/sec_groups.sh
index 49cb58f..f6810e3 100755
--- a/exercises/sec_groups.sh
+++ b/exercises/sec_groups.sh
@@ -35,7 +35,7 @@
 
 
 # Testing Security Groups
-# =============
+# =======================
 
 # List security groups
 nova secgroup-list