fix: log type as string (ipfs#306)

The value field is a string so it needs to be logged as `%s` - logging as `%b` will throw.

src/validator.ts

@@ -46,7 +46,7 @@ export const validate = async (publicKey: PublicKey, buf: Uint8Array): Promise<v
  throw errCode(new Error('unrecognized validity type'), ERRORS.ERR_UNRECOGNIZED_VALIDITY)
  }
 
- log('ipns record for %b is valid', record.value)
+ log('ipns record for %s is valid', record.value)
 }
 
 export async function ipnsValidator (key: Uint8Array, marshalledData: Uint8Array): Promise<void> {