Add runkit examples

Author: cblanc

README.md

@@ -2,6 +2,8 @@
 
 # Postcode.js
 
+[![Try postcode.js on RunKit](https://badge.runkitcdn.com/postcode.svg)](https://npm.runkit.com/postcode)
+
 Utility methods for UK Postcodes.
 
 Included is a test suite that tests against all postcodes listed in the Ordnance Survey's postcode dataset as of January 2014.

example.js

@@ -0,0 +1,14 @@
+const Postcode = require("postcode");
+
+const postcode = new Postcode("ec1v9lb");
+
+postcode.valid();
+postcode.normalise();
+
+postcode.outcode();
+postcode.incode();
+postcode.area();
+postcode.district();
+postcode.subDistrict();
+postcode.sector();
+postcode.unit();

package.json

@@ -13,6 +13,7 @@
     "prettier": "~1.16.4"
   },
   "files": ["index.js"],
+  "runkitExampleFilename": "example.js",
   "nyc": {
     "include": [
       "index.js"