Change docs for samemark so it complies with RT #128662

doc/Type/Str.pod6

@@ -721,15 +721,15 @@ Returns a copy of C<$string> with the mark/accent information for each
 character changed such that it matches the mark/accent of the corresponding
 character in C<$pattern>. If C<$string> is longer than C<$pattern>, the
 remaining characters in C<$string> receive the same mark/accent as the last
-character in C<$pattern>. This means that C<$pattern> must contain at least
-one character or an exception will be thrown.
+character in C<$pattern>. If C<$pattern> is empty no changes will be made.
 
 Examples:
 
     say 'åäö'.samemark('aäo');                        # aäo
     say 'åäö'.samemark('a');                          # aao
 
     say samemark('Pêrl', 'a');                        # Perl
+    say samemark('aöä', '');                          # aöä
 
 =head2 method succ