update copy

Author: ryanwaits

content/docs/stacks/clarinet-js-sdk/guides/mainnet-execution-simulation.mdx

@@ -112,7 +112,7 @@ The playground will execute the call against the latest mainnet state and displa
 
 While you can use Mainnet Execution Simulation (MXS) without an API key, you may run into rate limits that could disrupt your development workflow. We recommend using an API key to ensure reliable and uninterrupted access to MXS functionality.
 
-To use an API key with MXS, set the `HIRO_API_KEY` environment variable in your testing environment.
+To use an API key with MXS, set the `HIRO_API_KEY` environment variable in your terminal.
 
 ```terminal
 $ export HIRO_API_KEY="<your-api-key>"