Eliminates «<+» «>+» which were obsoleted

Since 2017.07:
https://github.com/rakudo/rakudo/blob/c66a6f0ec533e157a728afb90824c49704601f91/docs/ChangeLog#L793

Thanks to @lizmat for the heads up, this closes #2016

doc/Language/setbagmix.pod6

@@ -298,51 +298,6 @@ Equivalent to C«!(>)», at codepoint U+2285 (NOT A SUPERSET OF).
     say (1, 2, 3, 4).Set !(>) (3, 2, 1).Set; # OUTPUT: «False␤»
     say (1, 3).Set ⊅ (3, 2, 1).Set;          # OUTPUT: «True␤»
 
-=head3 infix (<+)
-
-    multi sub infix:<<(<+)>>(Any $a, Any $b --> Bool)
-    multi sub infix:<<(<+)>>(Baggy $a, Baggy $b --> Bool)
-
-X<Baggy subset of operator>.
-
-Returns C<True> if C<$a> is a Baggy B<subset> of C<$b>, i.e., if all the
-elements of C<$a> are in C<$b> and each element of C<$b> is weighed at
-least as heavily as the element is in C<$a>.
-
-    say (1, 2, 3).Bag (<+) (3, 2, 1).Bag;    # OUTPUT: «True␤»
-    say (1, 2, 2, 3).Bag (<+) (3, 2, 1).Bag; # OUTPUT: «False␤»
-
-=head3 infix ≼
-
-    only sub infix:<≼>($a, $b --> Bool)
-
-Alternate baggy subset of operator.
-
-Equivalent to L«(<+)», at codepoint U+227C (PRECEDES OR EQUAL TO).
-
-=head3 infix (>+)
-
-    multi sub infix:<<(>+)>>(Baggy $a, Baggy $b --> Bool)
-    multi sub infix:<<(>+)>>(Any $a, Any $b --> Bool)
-
-X<Baggy superset of operator>.
-
-Returns C<True> if C<$a> is a Baggy B<superset> of C<$b>, i.e., if all the
-elements of C<$b> are in C<$a> and no element of C<$b> is weighted heavier
-than that element is in C<$a>.
-
-    say (1, 2, 3).Bag (>+) (3, 2, 1).Bag;    # OUTPUT: «True␤»
-    say (1, 2, 2, 3).Bag (>+) (3, 2, 1).Bag; # OUTPUT: «True␤»
-    say (1, 2).Bag (>+) (3, 2, 1).Bag;       # OUTPUT: «False␤»
-
-=head3 infix ≽
-
-    only sub infix:<≽>($a, $b --> Bool)
-
-Alternate baggy superset of operator.
-
-Equivalent to L«(>+)», at codepoint U+227D (SUCCEEDS OR EQUAL TO).
-
 =head2 Operators that return C<Set> or C<Bag>
 
 =head3 infix (|)