Fix some legacy-style titles in documentation

Change-Id: Icbc74d9bc99be546f2c047a9098d7e453b2122a7
Signed-off-by: Michael Ochmann <michael.ochmann@sap.com>

Documentation/error-has-duplicates.txt

diff --git a/Documentation/error-has-duplicates.txt b/Documentation/error-has-duplicates.txt
index 8294c12..a520f5d 100644
--- a/Documentation/error-has-duplicates.txt
+++ b/Documentation/error-has-duplicates.txt
@@ -1,4 +1,4 @@
-= \... has duplicates
+= ... has duplicates
 
 With this error message Gerrit rejects to push a commit if its commit
 message contains a Change-Id for which multiple changes can be found