Dockerfile update with compose file and README materials

[ajatoledo]

1. Dockerfile change - I updated the ENTRYPOINT to remove the hard-coded output argument of output_http.so -w ./www and added it to the CMD input.

   • The update allows users to update stream parameters using command arguments as part of their docker call. Previously, users could not adjust output arguments without mapping a volume to their container.

   • Updated file path: ./mjpg-streamer/mjpg-streamer-experimental/Dockerfile

2. Example Docker Compose - Added an example docker-compose.yml to illustrate how to configure a container using an image built with the Dockerfile

3. Updated README - Added a new Docker section, which outlines how users can:

   1. Build an mjpg-streamer image using provided Dockerfile
   2. Create a container from the image using docker run
   3. Create a container from the image using docker compose