JSF 2 provides a new taglib.xml schema, and a new faces-config.xml schema, and comes with new files that describe the h: components and classes.

Here's how the action attribute/property is documented in each. As you can see, the faces-config documentation seems to be a superset of the taglib.xml one:

mojarra2\jsf-ri\conf\share\html_basic.taglib.xml [ taglib.xml ]

        <attribute>
            <description>
                MethodExpression representing the application action to invoke
                when this component is activated by the user. The expression
                must evaluate to a public method that takes no parameters, and
                returns an Object (the toString() of which is called to derive
                the logical outcome) which is passed to the NavigationHandler
                for this application.
            </description>
            <name>action</name>
            <required>false</required>
            <method-signature>java.lang.Object action()</method-signature>
        </attribute>

mojarra2\jsf-api\doc\standard-html-renderkit.xml

    <property>
      <description>
          MethodExpression representing the application action to invoke
          when this component is activated by the user. The expression
          must evaluate to a public method that takes no parameters, and
          returns an Object (the toString() of which is called to derive
          the logical outcome) which is passed to the NavigationHandler
          for this application.
        </description>
      <display-name>Application Action</display-name>
      <icon/>
      <property-name>action</property-name>
      <property-class>javax.el.MethodExpression</property-class>
      <property-extension>
        <method-signature>
                java.lang.Object action()
            </method-signature>
      </property-extension>
    </property>

Since the faces-config documentation provides more information than the old JSP style TLD, we should probably generate it, and find a way to create our HTML component documentation from it, hopefully using a pre-existing tool that Mojarra or MyFaces might be making use of themselves. Alternatively, we might consider generating our HTML documentation straight from our Meta classes. Lastly, we can simply shoe-horn our newer data into the TLD component description field, and continue using the existing tlddoc tool.