doc: add a link to test results

Author: ChALkeR

README.md

@@ -4,6 +4,7 @@
 [![](https://flat.badgen.net/github/release/ExodusOSS/bytes?icon=github)](https://github.com/ExodusOSS/bytes/releases)
 [![](https://flat.badgen.net/npm/dm/@exodus/bytes)](https://www.npmcharts.com/compare/@exodus/bytes?minimal=true)
 [![](https://flat.badgen.net/npm/license/@exodus/bytes)](https://github.com/ExodusOSS/bytes/blob/HEAD/LICENSE)
+[![](https://flat.badgen.net/github/checks/ExodusOSS/bytes/main?icon=github)](https://github.com/ExodusOSS/bytes/actions/workflows/test.yml?query=branch%3Amain)
 
 `Uint8Array` conversion to and from `base64`, `base32`, `base58`, `hex`, `utf8`, `utf16`, `bech32` and `wif`