Date the (==) operator

Also mention https://raku.land/zef:lizmat/Set::Equality as an alternative

doc/Language/setbagmix.rakudoc

@@ -180,12 +180,22 @@ Returns C<True> if C<$a> and C<$b> are B<identical>, else C<False>.
 L<More information|/language/operators#infix_(==),_infix_≡>,
 L<Wikipedia definition|https://en.wikipedia.org/wiki/Equality_(mathematics)#Equality_in_set_theory>.
 
+Available as of the 2020.07 Rakudo compiler release.  Users of older
+versions of Rakudo can install the
+L<Set::Equality|https://raku.land/zef:lizmat/Set::Equality> module for
+the same functionality.
+
 =head3 infix ≢
 
 Returns C<True> if C<$a> and C<$b> are B<not identical>, else C<False>.
 L<More information|/language/operators#infix_≢>,
 L<Wikipedia definition|https://en.wikipedia.org/wiki/Equality_(mathematics)#Equality_in_set_theory>.
 
+Available as of the 2020.07 Rakudo compiler release.  Users of older
+versions of Rakudo can install the
+L<Set::Equality|https://raku.land/zef:lizmat/Set::Equality> module for
+the same functionality.
+
 =head2 Set operators that return a C<QuantHash>
 
 =head3 infix (|), infix ∪