Augment CONTRIBUTING.md with steps on how to load the extension. Cred…

…it to iSeeU816 for the loading process, which can be found on issue #1625. (#1919)

CONTRIBUTING.md

@@ -27,3 +27,14 @@ Please use below template to report issue, or you could click menu item from Sur
 
     npm run build:dev                         # build development version
     browser=firefox npm run build:dev         # build development version for firefox
+
+## Load Extension
+
+To load the extension:
+1. Build using npm.
+2. Open the browser's extension page. 
+  - For Chrome, this can be accessed through "chrome://extensions".
+3. Disable the Surfingkeys extension that was installed from the Google Chrome Store.
+4. Enable "Developer mode" then click "Load unpacked."
+5. For versions prior to v1.x, navigate to `<pathToSurfingkeys>/dist/Chrome-extensions`
+6. For version v1.x, navigate to `<pathToSurfingkeys>/dist/<env>/<browser>`.