Update page.mdx (#6235)

Signed-off-by: Joaquim Verges <joaquim.verges@gmail.com>

Author: joaquim-verges

apps/portal/src/app/connect/pay/testing-pay/page.mdx

@@ -74,7 +74,11 @@ const { mutate: sendTransaction } = useSendTransaction({
 
 </Tabs>
 
-You can use the following information when using any provider in test mode:
+For Coinbase onramp, you can turn on "Mocked mode" when launching the Onramp experience. 
+
+At the bottom of the Onramp modal where it says "Secured by Coinbase", click 10 times on the word "Secured." This will navigate you to Onramp's Debug Menu. There, navigate to the Actions tab click on the toggle for "Enable Mocked Buy and Send." You can now exit the Debug Menu and proceed with mock buys and sends. Remember to click on the "Enable Mocked Buy and Send" toggle once you are done to enable actual buys and sends.
+
+For other providers, you can use the following information when using any provider in test mode:
 
 | Provider | Card Type    | Name        | Number              | Expiration Date | CVV          | Other Info                                                       |
 | -------- | ------------ | ----------- | ------------------- | --------------- | ------------ | ---------------------------------------------------------------- |