added questions to FAQ portion (#696)

* added questions to FAQ portion

* Update website/pages/en/billing.mdx

Co-authored-by: Benoît Rouleau <[email protected]>

* Update billing.mdx

* Update billing.mdx

* lint

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Co-authored-by: Benoît Rouleau <[email protected]>
Co-authored-by: azf20 <[email protected]>

Author: 3 people

website/pages/en/billing.mdx

@@ -191,6 +191,19 @@ We recommend you overestimate the number of queries you will need so that you do
 
 Of course, both new and existing users can reach out to Edge & Node's BD team for a consult to learn more about anticipated usage.
 
-### Can I withdrawal GRT from my billing balance?
+### Can I withdraw GRT from my billing balance?
 
-Yes, you can always withdrawal GRT that has not already been used for queries from your billing balance. The billing contract is only designed to bridge GRT from Ethereum mainnet to the Arbitrum network. If you'd like to transfer your GRT from Arbitrum back to Ethereum mainnet, you'll need to use the [Arbitrum Bridge](https://bridge.arbitrum.io/?l2ChainId=42161).
+Yes, you can always withdraw GRT that has not already been used for queries from your billing balance. The billing contract is only designed to bridge GRT from Ethereum mainnet to the Arbitrum network. If you'd like to transfer your GRT from Arbitrum back to Ethereum mainnet, you'll need to use the [Arbitrum Bridge](https://bridge.arbitrum.io/?l2ChainId=42161).
+
+### What happens when my billing balance runs? Will I get a warning?
+
+You will receive several email notifications before your billing balance runs out.
+
+### Which chain does GRT need to be on?
+
+Subgraph Studio's GRT billing is deployed on Arbitrum. You can bridge GRT and ETH from mainnet Ethereum using any of the following options:
+
+- [The Arbitrum Bridge](https://bridge.arbitrum.io/?l2ChainId=42161)
+- [TransferTo](https://transferto.xyz/swap)
+- [Connext Bridge](https://bridge.connext.network/)
+- [Hop Exchange](https://app.hop.exchange/#/send?token=ETH)