fix typos

Author: gfldex

doc/Type/Nil.pod6

@@ -8,7 +8,7 @@
 
 The value C<Nil> may be used to fill a spot where a value would normally
 go, and in so doing, explicitly indicate that no value is present. It
-may also used as a cheaper and less explosive alternative to a
+may also be used as a cheaper and less explosive alternative to a
 L<C<Failure>|/type/Failure>.  (In fact, class C<Failure> is derived from C<Nil>,
 so smartmatching C<Nil> will also match C<Failure>.)
 
@@ -24,7 +24,7 @@ is considered undefined for all other purposes.
     sub a( --> Int:D ) { return Nil }
     a().say;                    # Nil
 
-C<Nil> is what is returned from empty routines or clauses, or routines
+C<Nil> is what is returned from empty routines or closure, or routines
 that use a bare C<return> statement.
 
     sub a { }; a().say;         # Nil
@@ -52,7 +52,7 @@ C<Nil>.
 
 When assigned to a container, the C<Nil> value (but not any subclass of
 C<Nil>) will attempt to revert the container to its default value; if no
-such default is declared, Perl 6 assumes C<Any>. However, if the container's
+such default is declared, Perl 6 assumes C<Any>. However, if the container
 type is constrained with C<:D>, assigning C<Nil> to it will immediately throw
 an exception.  (In contrast, an instantiated C<Failure> matches C<:D>
 because it's a definite value, but will fail to match the actual nominal