Update the caller 5-to-6 info

Author: zostay

doc/Language/5to6-perlfunc.pod6

@@ -167,15 +167,28 @@ L<here|/language/control#proceed_and_succeed>.
 
 =item caller EXPR
 
-[NEEDS FURTHER RESEARCH] What C<caller> does in Perl 5 is taken on by
-C<callframe>. However, a simple call to C<callframe> will be of little
-use, as it will return a CallFrame object, rather than any useful
-information. The filename and line number returned as the second and
-third values from C<caller> in Perl 5, are in C<callframe.annotations>.
-You get them by using C<< callframe().annotations.<file line> >> or,
-individually, with C<< callframe().annotations.<file> >> and C<<
-callframe().annotations.<line> >>. There does not seem to be a simple
-way of getting the package name out of C<callframe> however.
+There are a couple different ways to get at caller information in Perl 6.
+The basic functionality is provided through L<callframe> now. However, Perl 6
+constructs call frames for regular blocks, not just for subroutines, so there
+are more frames to look through. The following will retrieve the basic
+information that C<caller> can return:
+
+    my $frame   = callframe(0); # OR just callframe()
+    my ($subroutine, $package);
+    if $frame.code ~~ Routine {
+        $subroutine = $frame.code.name;
+        $package    = $frame.code.package;
+    }
+    my $file    = $frame.file;
+    my $line    = $frame.line;
+
+Many of the other details returned by C<caller> are specific to Perl 5 and have
+no meaning in Perl 6.
+
+You can also get some of the information for the current frame or routine frame
+by using the dynamic variables L<&?ROUTINE>, L<&?BLOCK>, L<$?PACKAGE>,
+L<$?FILE>, and L<$?LINE>. For many purposes, L<Backtrace> may provide an easier
+way to browse through the call stack.
 
 =head2 chdir