feat: add user appointment stats endpoint to API root documentation

Add documentation for the new user-specific appointment statistics endpoint
to the API root view. This endpoint provides authenticated users with their
appointment analytics including total requests, pending reviews, scheduled,
rejected, and completed appointments along with completion rate.

The endpoint is available at /api/meetings/user/appointments/stats/ and
requires authentication via GET request.

booking_system/views.py

@@ -294,6 +294,20 @@ def api_root(request, format=None):
                 "completion_rate": "Percentage of requests that were scheduled"
             }
         },
+        "user_appointment_stats": {
+            "description": "Get appointment statistics and analytics for the authenticated user",
+            "url": request.build_absolute_uri("/api/meetings/user/appointments/stats/"),
+            "methods": ["GET"],
+            "authentication": "Required",
+            "response_fields": {
+                "total_requests": "Total number of appointment requests",
+                "pending_review": "Number of pending review requests",
+                "scheduled": "Number of scheduled appointments",
+                "rejected": "Number of rejected requests",
+                "completed": "Number of completed appointments",    
+                "completion_rate": "Percentage of requests that were scheduled"
+            }
+        },
         
     },
     "jitsi_integration": {