docs: fix image url typo in README.md (#479)

Author: chewong

README.md

@@ -15,7 +15,7 @@ Read the [documentation](https://lws.sigs.k8s.io/docs/) or watch the LWS-related
 
 ## Conceptual view
 
-![image](site/static/images/concepts.png)
+![image](site/static/images/concept.png)
 
 ## Feature overview
 

site/content/en/docs/overview/_index.md

@@ -6,7 +6,7 @@ menu:
   main:
     weight: 20
 description: >
-  An overview of the LeaderWorkerSet (LWS)
+  An overview of LeaderWorkerSet (LWS)
 ---
 
 LeaderWorkerSet (LWS) is an API for deploying a group of pods as a unit of replication. It aims to address common deployment patterns of AI/ML inference workloads, especially multi-host inference workloads where the LLM will be sharded and run across multiple devices on multiple nodes.