doc: contribute: remove example sub-header

Remove one level listing one single example.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>
diff --git a/doc/contribute/guidelines.rst b/doc/contribute/guidelines.rst
index 90357fe..a2c4fe4 100644
--- a/doc/contribute/guidelines.rst
+++ b/doc/contribute/guidelines.rst
@@ -370,11 +370,6 @@
 You need to change text in square brackets (``[like this]``) above to
 fit your commit.
 
-Examples and more details follow.
-
-Example
--------
-
 Here is an example of a good commit message.
 
 .. code-block:: none