tell limitations of Q and where they come from

doc/Language/quoting.pod6

@@ -23,15 +23,15 @@ Delimiters can be nested, but in the plain C<Q> form, backslash escapes
 aren't allowed.  In other words, basic C<Q> strings are as literal as
 possible.
 
-Some delimiters are not allowed immediately after C<Q>,
-C<q>, or C<qq>. Any characters that are allowed in
-L<identifiers|language/syntax#Identifiers>
-are not allowed to be used, since in such a case, the quoting
-construct together with such characters are interpreted as
-an identifier. In addition, C<( )> is not allowed because that is
-interpreted as a function call. If you still wish to use
-those characters as delimiters, separate them from C<Q>,
-C<q>, or C<qq> with a space.
+Some delimiters are not allowed immediately after C<Q>, C<q>, or C<qq>. Any
+characters that are allowed in L<identifiers|language/syntax#Identifiers> are
+not allowed to be used, since in such a case, the quoting construct together
+with such characters are interpreted as an identifier. In addition, C<( )> is
+not allowed because that is interpreted as a function call. If you still wish
+to use those characters as delimiters, separate them from C<Q>, C<q>, or C<qq>
+with a space. Please note that some natural languages use a left delimiting
+quote on the right side of a string. C<Q> will not support those as it relies
+on unicode properties to tell left and right delimiters apart.
 
 =for code :allow<B>
 B<Q'>this will not work!B<'>