Add `use_nil` to `encode_option`
A call to `jiffy:encode(Term, [use_nil]).` will currently cause dialyzer
to issue a warning because `use_nil` is not included in `encode_option`.
This appears to just be an omission.
diff --git a/src/jiffy.erl b/src/jiffy.erl
index 9871e4f..08fa3c0 100644
--- a/src/jiffy.erl
+++ b/src/jiffy.erl
@@ -46,6 +46,7 @@
-type encode_option() :: uescape
| pretty
| force_utf8
+ | use_nil
| escape_forward_slashes
| {bytes_per_iter, non_neg_integer()}
| {bytes_per_red, non_neg_integer()}.
