(DOCSP-46530) Fix short title underline error.

Author: elyse-mdb

source/troubleshooting/connection-errors.txt

@@ -123,7 +123,7 @@ to view possible solutions:
          http://portquiz.net:27017/.
 
          Atlas IP Access List Does Not Include Your Address
-         ````````````````````````````````````````````````
+         ``````````````````````````````````````````````````
 
          |service| only allows connections to a cluster from addresses
          listed in the project :atlas:`IP access list