Fix OptiTrack page discoverability and navigation link style

Author: nevalsar

_data/navigation.yml

@@ -179,8 +179,8 @@ wiki:
         url: /wiki/state-estimation/Cartographer-ROS-Integration/
       - title: Externally Referenced State Estimation for GPS Lacking Environments
         url: /wiki/state-estimation/gps-lacking-state-estimation-sensors.md
-      - title: Setting Up OptiTrack Motion Capture System with ROS
-        url: /wiki/state-estimation/optitrack-mocap.md
+      - title: Setting Up OptiTrack Mocap System
+        url: /wiki/state-estimation/optitrack-mocap/
   - title: Programming
     url:  /wiki/programming/
     children:

wiki/state-estimation/index.md

@@ -4,3 +4,8 @@ title: State Estimation
 ---
 **This page is a stub.** You can help us improve it by [editing it](https://github.com/RoboticsKnowledgebase/roboticsknowledgebase.github.io).
 {: .notice--warning}
+
+## Key Subsections and Highlights
+
+- **[Setting Up OptiTrack Mocap System](/wiki/state-estimation/optitrack-mocap/)**
+  Setup and integration guide for OptiTrack motion capture workflows with ROS and PX4 external position estimation.