Fix an obvious pasto s/create_method/create_type/ Also gloss up verbi…

…age in a couple places.

I'm assuming the example was correct, as opposed to the pod declarator, because it makes more sense that create_type would create a type.

lib/Type/Metamodel/Primitives.pod

@@ -25,9 +25,9 @@ of just one method called C<why>:
 
 =head1 Methods
 
-=head2 method create_method
+=head2 method create_type
 
-    method create_method(Mu $how, $repr = 'P6opaque')
+    method create_type(Mu $how, $repr = 'P6opaque')
 
 Creates and returns a new type from a meta object C<$how> and a representation
 name.
@@ -43,7 +43,7 @@ Sets the package associated with the type.
     method install_method_cache( Mu $type, %cache, :$authoritative = True)
 
 Installs a method cache, that is, a mapping from method names to code objects.
-If C<:authoritative> is missing, or set to C<True>, and calls of methods that
+If C<:authoritative> is missing, or set to C<True>, then calls of methods that
 do not exist in the cache willl throw an exception of type
 L<X::Method::NotFound|/type/X::Method::NotFound>. If C<:authoritative> is set
 to C<False>, the usual fallback mechanism are tried.
@@ -60,7 +60,7 @@ to C<False>, the usual fallback mechanism are tried.
 Configures the type checking for C<$type>. C<@cache> is a list of known types
 against which C<$type> checks positively (so in a classical class-based
 system, the type itself and all recursive superclasses). If C<:authoritative>
-is missing or C<True>, this type will fail to check against all types not in
+is missing or C<True>, this type will fail checks against all types not in
 C<@cache>. If C<:call_accepts> is True, the method L<ACCEPTS> will be called
 for type checks against this type.