auto build image (#147)

Auto build image when we run `docker compose up`, Make it start more
easy for beginner.

## Motivation and Context
When I try to use `docker compose up` start the MCP server, docker
default pull `registry` image from dockerhub, because I forget build
image first.

Maybe we don't need to manually build the image, just build it
automatically when docker compose starts

## How Has This Been Tested?
Just run `docker-compose up --build` at a environment has installed
docker and docker compose.

Signed-off-by: 疯魔慕薇 <kfanjian@gmail.com>
Co-authored-by: adam jones <domdomegg+git@gmail.com>

README.md

@@ -39,11 +39,8 @@ For development:
 The easiest way to get the registry running is to use `docker compose`. This will setup the MCP Registry service, import the seed data and run MongoDB in a local Docker environment.
 
 ```bash
-# Build the Docker image
-docker build -t registry .
-
 # Run the registry and MongoDB with docker compose
-docker compose up
+docker compose up --build
 ```
 
 This will start the MCP Registry service and MongoDB with Docker, exposing it on port 8080.

docker-compose.yml

@@ -2,6 +2,8 @@ services:
   registry:
     image: registry
     container_name: registry
+    build:
+      dockerfile: Dockerfile
     links:
       - mongodb
     depends_on: