Document multi ambiguity between int and uint

As veesh++ points out, multis cannot distinguish between `int` and `uint`
any more than they can distinguish between `int and `int64`.

Author: treyharris

doc/Language/nativetypes.pod6

@@ -55,14 +55,16 @@ counterparts:
 
 B<Note>: In v6.c, the default value for C<num> would have been a NaN.
 
-This is due to the fact that Natives don't know their types because they're just
-values, without any metadata. In
-L<multi-dispatch|/language/glossary#Multi-Dispatch>, you can have a native
-candidate, but you cannot differentiate different sizes of the same native type.
-That is, you can have an L<Int|/type/Int> and L<int|/type/int> candidates, but
-there would be an ambiguity between, for instance L<int|/type/int>,
-L<atomicint|/type/atomicint> or L<int64|/language/nativetypes#index-entry-int64>
-candidates.
+This is due to the fact that Natives don't know their types because
+they're just values, without any metadata. In
+L<multi-dispatch|/language/glossary#Multi-Dispatch>, you can have a
+native candidate, but you cannot differentiate different sizes or
+signedness of the same native type.  That is, you can have an
+L<Int|/type/Int> and L<int|/type/int> candidates, but there would be an
+ambiguity between, for instance L<int|/type/int>,
+L<uint|/language/nativetypes#index-entry-uint>,
+L<atomicint|/type/atomicint> or
+L<int64|/language/nativetypes#index-entry-int64> candidates.
 
 They cannot be bound either. Trying to do C<my num $numillo := 3.5> will
 raise the exception C<Cannot bind to natively typed variable