Add token usage tracking

Author: danbarr

docs/features/workspaces.mdx

@@ -36,6 +36,12 @@ Workspaces offer several key features:
   CodeGate security detections (alert history) are recorded in the active
   workspace, allowing you to track and review past interactions.
 
+- **Token usage tracking**: CodeGate tracks LLM token usage per workspace,
+  allowing you to monitor and analyze consumption across different contexts or
+  projects. For example, this feature can help you manage costs by identifying
+  high-usage workspaces or optimize API usage by adjusting prompts to reduce
+  token consumption.
+
 - **Isolation**: Configurations and data in one workspace do not affect others,
   providing clarity when reviewing your AI-assisted coding history and precision
   in tailoring your custom instructions.