chore: Mention npm run build in CONTRIBUTING.md (#232)

Author: CircuitCoder

CONTRIBUTING.md

@@ -3,7 +3,8 @@
 - Fork the repository on Github.
 - Clone the repository locally.
 - Make your changes to the code.
-- Run `npm install`.
+- Run `npm install` and `npm run build`.
 - Run `npm link` which creates a symlink and thereby `docsify` can be accessed globally.
+- After each edit, rerun `npm run build` so the new executable would be globally available.
 - We use [commitlint conventional naming rules](https://www.npmjs.com/package/@commitlint/config-conventional#rules) for our commits, make sure that you follow them.
 - Push to Github and open a pull request.