add: .env step (calcom#23572)

Author: bandhan-majumder

docs/developing/guides/api/how-to-setup-api-in-a-local-instance.mdx

@@ -19,6 +19,9 @@ To test the API in your local instance, you have the following pre-requisites:
     <Step title="Start development server and create API key">
         Start the cal.com server using `yarn dev` on localhost and create the test API keys by visiting `/settings/developer/api-keys`
     </Step>
+    <Step title="Copy .env.example file">
+       Copy the `.env.example` file to `.env` file by running `cp apps/api/v1/.env.example apps/api/v1/.env`from root folder
+    </Step>
     <Step title="Start API server and test API">
         Start the API server by running `yarn workspace @calcom/api dev` and start testing your API locally
     </Step>