values of ruletype field for update-policy statement
One document typo, version 9.18.21, doc/arm/reference.rst, line 7492, It is only 18 values from the list.
The ruletype field has 20 values: ``name``, ``subdomain``, ``zonesub``,
``wildcard``, ``self``, ``selfsub``, ``selfwild``, ``ms-self``,
``ms-selfsub``, ``ms-subdomain``, ``ms-subdomain-self-rhs``, ``krb5-self``,
``krb5-selfsub``, ``krb5-subdomain``, ``krb5-subdomain-self-rhs``,
``tcp-self``, ``6to4-self``, and ``external``.