Add some missing punctuation

lib/Type/Nil.pod

@@ -24,7 +24,7 @@ in an C<(Any)> object.
 	my Int $y = $x;		# error:	Type check failed in assignment to '$y'; expected 'Int' but got 'Any'
 
 This is because an untyped container is C<Any> until proven otherwise, and
-the C<Nil> evaporates
+the C<Nil> evaporates.
 
 If you are looking for a variable which transforms objects into type objects
 when said variable appears on the RHS, you can type the container as C<Nil>.
@@ -39,7 +39,7 @@ when said variable appears on the RHS, you can type the container as C<Nil>.
 
     method gist() returns Str:D
 
-Returns C<"Nil">
+Returns C<"Nil">.
 
 =head2 method Str