Added purchasing credits with USDC (#258)

Author: MadelineAu

docs/eigencompute/get-started/billing.md

@@ -3,7 +3,8 @@ title: Billing
 sidebar_position: 3
 ---
 
-Deploying an EigenCompute application to Sepolia testnet or mainnet requires an EigenCompute subscription.
+Deploying an EigenCompute application to Sepolia testnet or mainnet requires an EigenCompute subscription. EigenCompute subscriptions
+can be paid by credit card or EigenCompute credits can be purchased with USDC.
 
 EigenCompute has metered billing at 0.177c per vCPU hour so you pay for what you use. All new and migrating customers 
 receive a $100 credit.
@@ -27,7 +28,12 @@ To subscribe to EigenCompute:
 ecloud billing subscribe
 ```
 
-The payment portal is displayed.  Enter your payment method details and click the Subscribe button.
+Choose whether to subscribe with credit card or by purchasing credits with USDC. 
+
+If you select credit card, the payment portal is displayed.  Enter your payment method details and click the Subscribe button.
+
+If you select purchase credits with USDC, the EigenCompute wallet address and balance is displayed. If the wallet contains USDC,
+specify the amount to spend on credits. If the wallet does not contain USDC, you are prompted to send USDC to the wallet.
 
 The payment successful message is displayed.  Return to the terminal and you have access to [deploy your application](../reference/ecloud-cli/compute/app.md#deploy).
 
@@ -52,6 +58,17 @@ ecloud billing status
 
 The subscription status is displayed and a link provided to manage payment methods and view subscription transactions.
 
+## Top up with USDC
+
+To purchase EigenCompute credits with USDC:
+
+```
+ecloud billing top-up
+```
+
+The EigenCompute wallet address and balance is displayed. If the wallet contains USDC, specify the amount to spend on credits. 
+If the wallet does not contain USDC, you are prompted to send USDC to the wallet.
+
 ## Support
 
 For support, join our [Discord channel](https://discord.com/channels/1089434273720832071/1187153894564966480).

docs/eigencompute/reference/ecloud-cli/billing.md

@@ -10,6 +10,7 @@ EigenCompute requires a [subscription for deploying applications](../../get-star
 * [subscribe](#subscribe)
 * [cancel](#cancel) 
 * [status](#status)
+* [top-up](#top-up)
 
 ## Global Options
 
@@ -58,3 +59,6 @@ Display current billing status. For more information, refer to [Manage Billing](
 
 `ecloud billing status [global options]`
 
+## top-up
+
+Purchase EigenCompute credits with USDC. For more information, refer to [Manage Billing](../../get-started/billing#top-up-with-usdc)