Fix 2 typos

Author: lizmat

doc/Language/setbagmix.pod6

@@ -51,7 +51,7 @@ The six collection classes C<Set>, C<SetHash>, C<Bag>, C<BagHash>, C<Mix>,
 C<MixHash>, all share similar semantics.
 
 For one thing, as far as they are concerned, identical objects refer to the
-same element – where identity is determined using the L<WHICH|/routine/WHICH> methods
+same element – where identity is determined using the L<WHICH|/routine/WHICH> method
 (i.e. the same way that the L<===> operator checks identity). For value
 types like C<Str>, this means having the same value; for reference types
 like C<Array>, it means referring to the same object instance.
@@ -72,7 +72,7 @@ associated weights are the 'values':
 
 =comment TODO: Update this after ab5tract's set/bag/mix operator redesign.
 
-There are many infixes devoted to preforming common operations on
+There are many infixes devoted to performing common operations on
 L<C<Set>s|Set>, such as unions and set differences. Other operations include
 boolean checks, like whether an object is an element of a C<Set>, or whether
 one C<Set> is a subset of another C<Set>.