Tweak billing (#611)

* Tweak billing

Context: new direction for billing docs will be that they're written under the assumption that everything happens on Arbitrum One.

* getting eth

* updates

Author: MichaelMacaulay

website/pages/en/billing.mdx

@@ -149,10 +149,10 @@ You can learn more about getting GRT on Binance [here](https://www.binance.com/e
 
 This is how you can purchase GRT on Uniswap.
 
-1. Go to [Uniswap](https://app.uniswap.org/#/swap) and connect your wallet.
+1. Go to [Uniswap](https://app.uniswap.org/swap?chain=arbitrum) and connect your wallet.
 2. Select the token you want to swap from. Select ETH.
 3. Select the token you want to swap to. Select GRT.
-   - Make sure you're swapping for the correct token. The GRT smart contract address is: `0xc944E90C64B2c07662A292be6244BDf05Cda44a7`
+   - Make sure you're swapping for the correct token. The GRT smart contract address on Arbitrum One is: [0x9623063377AD1B27544C965cCd7342f7EA7e88C7](https://arbiscan.io/token/0x9623063377ad1b27544c965ccd7342f7ea7e88c7)
 4. Enter the amount of ETH you want to swap.
 5. Click "Swap".
 6. Confirm the transaction in your wallet and you wait for the transaction to process.
@@ -179,6 +179,7 @@ This will be a step by step guide for purchasing ETH on Coinbase.
     - To transfer the ETH to your crypto wallet, click on the "Accounts" button on the top right of the page.
     - Click on the "Send" button next to the ETH account.
     - Enter the amount of ETH you want to send and the wallet address you want to send it to.
+    - Ensure that you are sending to your Ethereum wallet address on Arbitrum One.
     - Click "Continue" and confirm your transaction.
 
 You can learn more about getting ETH on Coinbase [here](https://help.coinbase.com/en/coinbase/trading-and-funding/buying-selling-or-converting-crypto/how-do-i-buy-digital-currency).
@@ -199,6 +200,7 @@ This will be a step by step guide for purchasing ETH on Binance.
     - To withdraw the ETH to your crypto wallet, add your crypto wallet's address to the withdrawal whitelist.
     - Click on the "wallet" button, click withdraw, and select ETH.
     - Enter the amount of ETH you want to send and the whitelisted wallet address you want to send it to.
+    - Ensure that you are sending to your Ethereum wallet address on Arbitrum One.
     - Click "Continue" and confirm your transaction.
 
 You can learn more about getting ETH on Binance [here](https://www.binance.com/en/support/faq/how-to-buy-cryptocurrency-on-binance-homepage-400c38f5e0cd4b46a1d0805c296b5582).