fix Evolution submenu name in email-clients.txt

I have noticed that there is no submenu in Evolution called Heading
instead there is Paragraph style

Signed-off-by: Ahmed Mohamed <ahmedsoliman0x666@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/email-clients.txt

@@ -93,7 +93,7 @@ Evolution (GUI)
 Some people use this successfully for patches.
 
 When composing mail select: Preformat
-  from Format->Heading->Preformatted (Ctrl-7)
+  from Format->Paragraph Style->Preformatted (Ctrl-7)
   or the toolbar
 
 Then use: