docs: add Unkey rate limiting setup documentation (calcom#27163)

- Update .env.example with clarified Unkey configuration comments
- Update README.md with explainer of Unkey and how it's optional.

Author: perkinsjr

.env.example

@@ -398,7 +398,10 @@ NEXT_PUBLIC_API_V2_URL="http://localhost:5555/api/v2"
 TASKER_ENABLE_WEBHOOKS=0
 TASKER_ENABLE_EMAILS=0
 
-# Ratelimiting via unkey
+# Ratelimiting via Unkey (https://unkey.com)
+# Optional: Only required if you want to enable rate limiting
+# Not needed for testing or self-hosting unless you specifically want rate limiting features
+# Sign up at https://unkey.com to get your Root key
 UNKEY_ROOT_KEY=
 
 # Used for Cal.ai Voice AI Agents

README.md

@@ -888,6 +888,19 @@ following
 
 [Follow these steps](./packages/app-store/pipedrive-crm/)
 
+### Rate Limiting with Unkey
+
+Cal.com uses [Unkey](https://unkey.com) for rate limiting. This is an optional feature and is not required for testing or self-hosting.
+
+If you want to enable rate limiting:
+
+1. Sign up for an account at [unkey.com](https://unkey.com)
+2. Create a Root key with permissions for 
+   `ratelimit.create_namespace` and `ratelimit.limit`
+3. Copy the root key to your `.env` file into the `UNKEY_ROOT_KEY` field
+
+Note: If you don't configure Unkey, Cal.com will work normally without rate limiting enabled.
+
 ## Workflows
 
 ### Setting up SendGrid for Email reminders