docs: mermaid chart for kv cache manager on 'llm-d.ai' (#93)

Signed-off-by: Zerohertz <[email protected]>

Author: Zerohertz

README.md

@@ -47,13 +47,13 @@ graph TD
         G[...]
     end
 
-    A -->|"(1) Score(prompt, pods)"| B
-    B -->|"(2) Query Index"| C
-    B -->|"(3) Return Scores"| A
+    A--"(1) Score(prompt, pods)"-->B
+    B--"(2) Query Index"-->C
+    B--"(3) Return Scores"-->A
     
-    E -->|"(A) Emit KVEvents"| D
-    F -->|"(A) Emit KVEvents"| D
-    D -->|"(B) Update Index"| C
+    E--"(A) Emit KVEvents"-->D
+    F--"(A) Emit KVEvents"-->D
+    D--"(B) Update Index"-->C
 ```
 **Read Path:**
 - (1)  **Scoring Request**: A scheduler asks the **KVCache Indexer** to score a set of pods for a given prompt