Build a wallet using js - JS Bounty (#1752)

Created javascript tutorial with feedback from @mDuo13 and @JST5000 to teach folks how to build a wallet for the xrpl using javascript.

content/_code-samples/build-a-wallet/js/README.md

@@ -0,0 +1,24 @@
+# Pre-requisites
+
+To implement this tutorial you should have a basic understanding of JavaScript and Node.js. You should also have a basic idea about XRP Ledger. For more information, visit the [XRP Ledger Dev Portal](https://xrpl.org) and the [XRPL Learning Portal](https://learn.xrpl.org/) for videos, libraries, and other resources.
+
+Follow the steps below to get started:
+
+1. [Node.js](https://nodejs.org/en/download/) (v10.15.3 or higher)
+2. Install [Yarn](https://yarnpkg.com/en/docs/install) (v1.17.3 or higher) or [NPM](https://www.npmjs.com/get-npm) (v6.4.1 or higher)
+3. Add your Seed, Client, and specify testnet/mainnet in .env file. Example .env file is provided in the repo.
+4. Run `yarn install` or `npm install` to install dependencies
+5. Start the app with `yarn dev` or `npm dev`
+
+# Goals
+
+At the end of this tutorial, you should be able to build a simple XRP wallet that can:
+
+- Shows updates to the XRP Ledger in real-time.
+- Can view any XRP Ledger account's activity "read-only" including showing how much XRP was delivered by each transaction.
+- Shows how much XRP is set aside for the account's reserve requirement. 
+- Can send direct XRP payments, and provides feedback about the intended destination address, including:
+  - Displays available balance in your account
+  - Verifies that the destination address is valid
+  - Validates amount input to ensure it is a valid number and that the account has enough XRP to send
+  - Allows addition of the destination tag