GEP-3539: a few fixes

* Fix missing image
* Change GEP status to Memorandum
* Make GEP navigable
* Crop trailing whitespace from images

Signed-off-by: Pooja [email protected]

Author: ptrivedi

geps/gep-3539/images/LB-NP-Clusterip.png

@@ -1,7 +1,7 @@
 # GEP-3539: ClusterIP Gateway - Gateway API to Expose Pods on Cluster-Internal IP Address
 
 * Issue: [#3539](https://github.com/kubernetes-sigs/gateway-api/issues/3539)
-* Status: Experimental
+* Status: Memorandum
 
 ## TLDR
 

geps/gep-3539/images/gatewayclasses-lb-np.png

@@ -168,6 +168,7 @@ nav:
       - geps/gep-2659/index.md
       - geps/gep-2722/index.md
       - geps/gep-2907/index.md
+      - geps/gep-3539/index.md
     - Declined:
       - geps/gep-735/index.md
       - geps/gep-1282/index.md