docs(json-pack): ✏️ add Bencode README

Author: streamich

src/json-pack/bencode/README.md

@@ -0,0 +1,22 @@
+# Bencode codecs
+
+Implements [Bencode][bencode] encoder and decoder.
+
+[bencode]: https://en.wikipedia.org/wiki/Bencode
+
+Type coercion:
+
+- Strings and `Uint8Array` are encoded as Bencode byte strings, decoded as `Uint8Array`.
+- `Object` and `Map` are encoded as Bencode dictionaries, decoded as `Object`.
+- `Array` and `Set` are encoded as Bencode lists, decoded as `Array`.
+- `number` and `bigint` are encoded as Bencode integers, decoded as `number`.
+- Float `number` are rounded and encoded as Bencode integers, decoded as `number`.
+
+
+## Extensions
+
+This codec extends the Bencode specification to support the following types:
+
+- `null` (encoded as `n`)
+- `undefined` (encoded as `u`)
+- `boolean` (encoded as `t` for `true` and `f` for `false`)