Changed real infix to imaginary one

This kind of solves #1394, creating in its turn a broken link, but at
least it should show the actual documentation for the Z infix.

Closes #1394 if everything goes well.

Author: JJ

doc/Language/about.pod6

@@ -97,37 +97,37 @@ Documentables may contain other documentables. Class documentables, for
 example, often contain the methods the class implements.
 
 Definitions must be in one of the following forms to be recognized as
-the start of a documentable named, say, Z.  First the code in the document source:
+the start of a documentable named, say, þ.  First the code in the document source:
 
 =begin code :skip-test
 
-=item X<C<How to use the Z infix> | infix,Z> (This a special case, which
+=item X<C<How to use the þ infix> | infix,þ> (This a special case, which
 is always considered a definition)
 
-=item C<The Z Infix>
+=item C<The þ Infix>
 
-=item B<The C<Z> Infix>
+=item B<The C<þ> Infix>
 
-=item C<Infix Z>
+=item C<Infix þ>
 
-=item B<Infix C<Z>>
+=item B<Infix C<þ>>
 
 =item C<trait is cached> (A special case for the L<trait|/language/functions#Traits> documentables)
 
 =end code
 
 Then the results on the rendered page:
 
-=item X<C<How to use the Z infix> | infix,Z> (This is a special case, which
+=item X<C<How to use the þ infix> | infix,þ> (This is a special case, which
 is always considered a definition)
 
-=item C<The Z Infix>
+=item C<The þ Infix>
 
-=item B<The C<Z> Infix>
+=item B<The C<þ> Infix>
 
-=item C<Infix Z>
+=item C<Infix þ>
 
-=item B<Infix C<Z>>
+=item B<Infix C<þ>>
 
 =item C<trait is cached> (A special case for the L<trait|/language/functions#Traits> documentables)