fix markdown

Author: stevebux

tests/e2e-tests/README.md

@@ -1,6 +1,6 @@
 # E2E Tests
 
-### Set Proxy Name
+## Set Proxy Name
 
 Set the `PROXY_NAME` environment variable to specify the environment for test execution. You can find the proxy name by logging into [Apigee](https://apigee.com/edge), navigating to 'API Proxies' and searching for 'supplier-api' for lower environments like internal-dev.
 
@@ -13,7 +13,7 @@ Available values for `PROXY_NAME` include:
 * `nhs-notify-supplier--internal-dev--nhs-notify-supplier`
 * `nhs-notify-supplier--internal-dev--nhs-notify-supplier-pr<num>`
 
-### Set Up API Keys
+## Set Up API Keys
 
 Set the following environment variables to use the Apigee API keys: