docs: add LiteLLM license key environment variable instructions

Added a new section to the config.yaml documentation explaining how to
set the LITELLM_LICENSE environment variable for enterprise features.

Co-authored-by: Krish Dholakia <krrishdholakia@gmail.com>

docs/my-website/docs/proxy/configs.md

@@ -602,6 +602,22 @@ Since you shouldn't use 12.5, round down to **10** to leave a safety buffer. Thi
 - Total maximum connections: 8 workers × 10 connections = 80 connections
 - This stays safely under your database's 100 connection limit
 
+## LiteLLM License Key (Enterprise)
+
+To enable [LiteLLM Enterprise features](https://docs.litellm.ai/docs/proxy/enterprise), set your license key as an environment variable:
+
+```bash
+export LITELLM_LICENSE="eyJ..."
+```
+
+The license key is a JWT token provided when you purchase a LiteLLM Enterprise license. Once set, LiteLLM will automatically detect and activate enterprise features.
+
+You can also add it to your `.env` file:
+
+```env
+LITELLM_LICENSE="eyJ..."
+```
+
 ## Extras