Improve doc of postfix:<.+> and postfix:<.*>

Close #1421. Co. rakudo/rakudo#1754

Author: tisonkun

doc/Language/operators.pod6

@@ -637,19 +637,39 @@ Technically, not a real operator; it's syntax special-cased in the compiler.
 X«|postfix .+»
 =head2 postfix C«.+»
 
-C<$invocant.+method> calls all methods called C<method> from C<$invocant>,
-and returns a L<List> of the results. Dies if no such method was found.
+C<$foo.+meth> walks the MRO and calls all the methods called C<meth> and submethods called C<meth> if the type is the same as type of C<$foo>.
+Those methods might be multies, in which case the matching candidate
+would be called.
 
-Technically, not a real operator; it's syntax special-cased in the compiler.
+After that, a L<List> of the results are returned. If no such method was found,
+it throws a L<X::Method::NotFound> exception.
+
+    class A {
+      method foo { say "from A"; }
+    }
+    class B is A {
+      multi method foo { say "from B"; }
+      multi method foo(Str) { say "from B (Str)"; }
+    }
+    class C is B is A {
+      multi method foo { say "from C"; }
+      multi method foo(Str) { say "from C (Str)"; }
+    }
+
+    say C.+foo; # OUTPUT: «from C␤from B␤from A␤(True True True)␤»
 
 X«|postfix .*»
 =head2 postfix C«.*»
 
-C<$invocant.*method> calls all methods called C<method> from C<$invocant>,
-and returns a L<List> of the results. If no such method was found, an empty
-L<List> is returned.
+C<$foo.*meth> walks the MRO and calls all the methods called C<meth> and submethods called C<meth> if the type is the same as type of C<$foo>.
+Those methods might be multies, in which case the matching candidate
+would be called.
 
-Technically, not a real operator; it's syntax special-cased in the compiler.
+After that, a L<List> of the results are returned. If no such method was found,
+an empty L<List> is returned.
+
+Technically, postfix C<.+> calls C<.*> at first. Read postfix C<.+> section to
+see examples.
 
 X<|postfix ».>X«|postfix >>.»
 =head2 postfix C<».> / postfix C«>>.»