Docs: token usage progress bar for desktop (#2600)

Co-authored-by: Angie Jones <jones.angie@gmail.com>

documentation/docs/guides/smart-context-management.md

@@ -97,4 +97,25 @@ Key information has been preserved while reducing context length.
 </Tabs>
 
   </TabItem>
+</Tabs>
+
+### Token usage
+<Tabs>
+    <TabItem value="ui" label="Goose Desktop" default>
+    After sending your first message to Goose, a colored circle appears next to the model name at the bottom of the session window. The color provides a visual indicator of your token usage for the session. 
+      - **Green**: Normal usage - Plenty of context space available
+      - **Orange**: Warning state - Approaching limit (80% of capacity)
+      - **Red**: Error state - Context limit reached
+    
+    Hover over this circle to display:
+      - the number of tokens used
+      - the percentage of available tokens used
+      - the total available tokens
+      - A progress bar showing your current token usage
+        
+    </TabItem>
+    <TabItem value="cli" label="Goose CLI">
+        This functionality is not available in the Goose CLI. 
+
+    </TabItem>
 </Tabs>