Update source/security/authentication.txt

Co-authored-by: Jordan Smith <[email protected]>

Author: mongoKart

source/security/authentication.txt

@@ -52,6 +52,7 @@ a mechanism to learn more about how to use it with your application.
 .. list-table::
    :header-rows: 1
    :stub-columns: 1
+   :widths: 40 20 20 20
 
    * - Authentication Mechanism
      - Atlas