DOCS-12514 incorrect instruction and spelling for Kerberos (#6137)

Author: kennethdyer

source/tutorial/control-access-to-mongodb-with-kerberos-authentication.txt

@@ -74,7 +74,7 @@ KRB5_KTNAME
 
 If you installed MongoDB Enterprise using one of the official ``.deb``
 or ``.rpm`` packages, and you use the included init/upstart scripts to
-control the :binary:`~bin.mongod` instance, you can set the ``KR5_KTNAME``
+control the :binary:`~bin.mongod` instance, you can set the ``KRB5_KTNAME``
 variable in the default environment settings file instead of setting
 the variable each time.
 
@@ -87,7 +87,7 @@ Set the ``KRB5_KTNAME`` value in a line that resembles the following:
 
 .. code-block:: javascript
 
-   export KRB5_KTNAME="<path to keytab>"
+   KRB5_KTNAME="<path to keytab>"
 
 Configure ``mongos`` for Kerberos
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~