Refs CallFrame from variables, closes #885

Author: JJ

doc/Language/variables.pod6

@@ -1073,8 +1073,8 @@ the program.
 The most common compile time variables are the following:
 
 =for table
-    $?FILE         Which file am I in?
-    $?LINE         Which line am I at?
+    $?FILE         Which file am I in? Also available as <C<callframe.file>|type/CallFrame#method_file>
+    $?LINE         Which line am I at? Also available as <C<callframe.line>|type/CallFrame#method_line>
     ::?CLASS       Which class am I in?
     %?LANG         What is the current set of interwoven languages?
     %?RESOURCES    The files associated with the "Distribution" of the current compilation unit.