Add types to package.json and typedef for payload (#25)

Author: timidak

package.json

@@ -4,6 +4,7 @@
   "description": "Send analytics signals to TelemetryDeck",
   "main": "dist/telemetrydeck.cjs",
   "module": "dist/telemetrydeck.js",
+  "types": "dist/telemetrydeck.d.ts",
   "files": [
     "dist/*",
     "README.md",

src/telemetrydeck.js

@@ -16,6 +16,10 @@ import { version } from './utils/version.js';
  * @property {Function} [subtleCrypto] Used for providing an alternative implementation of SubtleCrypto where no browser is available. Expects a class providing a `.digest(method, value)` method.
  */
 
+/**
+ * @typedef {Object.<string, any>} TelemetryDeckPayload
+ */
+
 export default class TelemetryDeck {
   appID = '';
   clientUser = '';