methods: Remove req for few method-specific-id formats

This should be up to the DID method, doesn't make sense to
constrain it as it is internal to DID method (no affect on
interop); and "as possible" is not testable. See #384"

index.html

@@ -3043,9 +3043,7 @@ <h2>Method Schemes</h2>
 
       <p>
 If needed, a method-specific <a>DID scheme</a> MAY define multiple
-<code>method-specific-id</code> formats. It is RECOMMENDED that a
-method-specific <a>DID scheme</a> define as few <code>method-specific-id</code>
-formats as possible.
+<code>method-specific-id</code> formats.
       </p>
 
       <p>