Changes another variable name.

doc/Type/Metamodel/Primitives.pod6

@@ -82,7 +82,7 @@ for what C<$configuration> can contain (until we have better docs, sorry).
     method rebless(Mu $object, Mu $type)
 
 Changes C<$object> to be of type C<$type>. This only works if C<$type>
-type-checks against the current type of C<$obj>, and if the storage of
+type-checks against the current type of C<$object>, and if the storage of
 C<$object> is a subset of that of C<$type>. N<As of Raku 2019.11, this method
  requires
 L<special arrangements|https://github.com/rakudo/rakudo/issues/3414#issuecomment-573251877>>.