Clarify auth string

Author: JJ

doc/Language/typesystem.pod6

@@ -942,7 +942,11 @@ C«:auth<>», and C«:api<>» respectively. All of them take a string as argumen
 for C<:ver> the string is converted to a L«C«Version»|/type/Version» object, and
 for C<:api> the string is converted into an
 L<allomorph|/language/glossary#index-entry-Allomorph>
-L«C«IntStr»|/type/IntStr» object. To query the version, author, and API version
+L«C«IntStr»|/type/IntStr» object. C<:auth> generally takes the form
+C<hosting:ID>, as in C<github:githubnick> or C<gitlab:gitlab-user>.
+
+
+To query the version, author, and API version
 of a type use L<C<.^ver>|/type/Metamodel::Versioning#method_ver>,
 L<C<.^auth>|/type/Metamodel::Versioning#method_auth>, and
 L<C<.^api>|/type/Metamodel::Versioning#method_api> respectively, as illustrated