Add infix C«(<=)», infix C«⊆», infix C«⊈» to operators

doc/Language/operators.pod6

@@ -2282,6 +2282,42 @@ C«!(<)».
 
 C«⊄» is codepoint U+2284 (NOT A SUBSET OF).
 
+=head2 infix C«(<=)», infix C«⊆»
+
+    multi sub infix:<(<=)>($a,$b --> Bool:D)
+    multi sub infix:<⊆>($a,$b --> Bool:D)
+
+X<Subset of or equal to operator>.
+
+Returns C<True> if C<$a> is a B<subset> of C<$b>, i.e., that all the
+elements of C<$a> are elements of C<$b> but C<$a> is a smaller or equal sized
+set than C<$b>.
+
+    =begin code
+    say (1,2,3) (<=) (2,3,1); # OUTPUT: «True␤»
+    say (2,3) (<=) (2,3,1); # OUTPUT: «True␤»
+    say 4 ⊆ (1,2,3); # OUTPUT: «False␤»
+    =end code
+
+C«⊆» is equivalent to C«(<=)», at codepoint U+2286 (SUBSET OF OR EQUAL TO).
+
+=head2 infix C«⊈»
+
+    multi sub infix:<⊈>($a,$b --> Bool:D)
+
+X<Not a subset of nor equal to operator>.
+
+Returns C<True> if C<$a> is B<not> a C<subset> of C<$b>.  Equivalent to
+C«!(<=)».
+
+    =begin code
+    say (1,2,3) ⊄ (2,3,1); # OUTPUT: «True␤»
+    say (2,3) ⊄ (2,3,1); # OUTPUT: «False␤»
+    say 4 !(<=) (1,2,3); # OUTPUT: «True␤»
+    =end code
+
+C«⊈» is codepoint U+2288 (NEITHER A SUBSET OF NOR EQUAL TO).
+
 =head1 Tight AND precedence
 
 =head2 infix C«&&»
@@ -3226,31 +3262,6 @@ This summary those operators are included for completeness.
 
 =head2 Operators that return C<Bool>
 
-=head3 infix (<=)
-
-X<Subset of or equal to operator>.
-
-Returns C<True> if C<$a> is a B<subset> or B<is equal to> C<$b>.
-
-=head3 infix ⊆
-
-Alternate X<subset of or equal to operator>.
-
-Equivalent to L«(<=)».
-
-=head3 infix !(<=)
-
-X<Neither subset of nor equal to operator>.
-
-Returns C<True> if C<$a> is a B<not a subset> or B<is not equal> to C<$b>.
-
-=head3 infix ⊈
-
-Alternate X<neither subset of nor equal to operator>, at codepoint U+2288
-(NEITHER A SUBSET OF NOR EQUAL TO).
-
-Equivalent to C«!(<=)».
-
 =head3 infix (>=)
 
 X<Superset of or equal to operator>.