Make overview navigable (#919)

Small update. This just makes the `overview` items links, which improves
the ability to navigate our doc for different sections.

docs/shortfin/llm/user/llama_serving.md

@@ -32,12 +32,12 @@ shark-ai.
 
 Overview:
 
-1. Setup, installing dependencies and configuring the environment
-2. Download model files then compile the model for our accelerator(s) of choice
-3. Start a server using the compiled model files
-4. Send chat requests to the server and receive chat responses back
-5. Running with sharded models
-6. Server options
+1. [Setup, installing dependencies and configuring the environment](#1-setup)
+2. [Download model files then compile the model for our accelerator(s) of choice](#2-download-and-compile-the-model)
+3. [Start a server using the compiled model files](#3-run-the-shortfin-llm-server)
+4. [Send chat requests to the server and receive chat responses back](#4-test-the-server)
+5. [Running with sharded models](#5-running-with-sharded-models)
+6. [Server options](#6-server-options)
 
 ## 1. Setup