Add $¢ to the list of always available lexical var (#4459)

* Add $¢ to the list of always available lexical var

Author: coke

doc/Language/variables.rakudoc

@@ -1112,18 +1112,22 @@ short.
 
 =head2 Pre-defined lexical variables
 
-There are three special variables that are always available:
+There are four special variables that are always available:
 
 =begin table
 
     Variable    Meaning            Scope
 
-    $_          topic variable     every block
-    $/          regex match        every sub / method
-    $!          exceptions         every sub / method
+    $_          topic variable               every block
+    $/          regex match                  every sub / method
+    $!          exceptions                   every sub / method
+    $¢          last match (similar to $/)   inside current regex
 
 =end table
 
+I<Note that while you can access C<$¢> without error anywhere, it will
+contain C<Nil> if accessed outside of a regex>.
+
 X<|Language,topic variable>
 =head3 The C<$_> variable
 
@@ -1295,6 +1299,11 @@ the block to the caught exception.
 Also note that the same thread-safety issues apply to the use of C<$!> as
 they do to C<$/>.
 
+X<|Language,cursor variable>
+=head3 The C<$¢> variable
+
+See the description in L<Match|/type/Match#index-entry-$%C2%A2-$%C2%A2>.
+
 X<|Variables,$?FILE>X<|Variables,$?LINE>X<|Variables,::?CLASS>
 
 =head2 Compile-time variables