DOCSP-28231: hostname canonicalization options for kerberos (#633)

* DOCSP-28231: add values for canonicalize_host_name to Kerberos auth

* concept fix

* MW PR fixes 1

Author: rustagir

source/fundamentals/authentication/enterprise-mechanisms.txt

@@ -24,15 +24,23 @@ authentication mechanism available in the MongoDB Enterprise Edition:
 The ``GSSAPI`` authentication mechanism uses your user principal to
 authenticate to a Kerberos service.
 
-You can specify this authentication mechanism by setting the following
-parameters of the
+You can specify this authentication mechanism by performing the
+following actions while specifying options on your
 :manual:`connection string </reference/connection-string/>`:
 
-- Set the ``authMechanism`` parameter to ``GSSAPI``
+- Set the ``authMechanism`` parameter to ``GSSAPI``.
 - Set the ``SERVICE_NAME`` value in the ``authMechanismProperties``
-  parameter if using a value other than ``mongodb``
+  parameter if using a value other than ``mongodb``.
 - Specify a ``SERVICE_REALM`` value in the ``authMechanismProperties``
   parameter if a custom service realm is required.
+- Specify a ``CANONICALIZE_HOST_NAME`` value in the ``authMechanismProperties``
+  parameter if canonicalization of the hostname is required. This property can take
+  the following values:
+
+  - ``none``: (Default) Does not perform hostname canonicalization
+  - ``forward``: Performs a forward DNS lookup to canonicalize the hostname
+  - ``forwardAndReverse``: Performs a forward DNS lookup and then a
+    reverse lookup on that value to canonicalize the hostname
 
 .. important::
 
@@ -58,7 +66,8 @@ The following code sample authenticates to Kerberos for UNIX using ``GSSAPI``.
    const clusterUrl = "<MongoDB cluster URL>";
    const principal = encodeURIComponent("<Kerberos principal and realm>");
    const serviceRealm = "<Kerberos service realm>";
-   const authMechanismProperties = `SERVICE_REALM:${serviceRealm}`;
+   const canonicalizationSetting = "<canonicalization setting>";
+   const authMechanismProperties = `SERVICE_REALM:${serviceRealm},CANONICALIZE_HOST_NAME:${canonicalizationSetting}`;
 
    const authMechanism = "GSSAPI";