Update README and fix docker scripts

[jhanca-robotecai]

What does this PR do?

This PR fixes multiple small issues of the codebase on the development branch to get a working release with O3DE 2409.1. This PR targets the development branch, but the merge to main will follow instantly.

The changes include the following:

• docker scripts changed to pull all repositories that are currently needed
• docker scripts changed to pull stable release of the demo and all other branches instead of the development
• default level is stored in the registry file instead of the obsolete autoexec (this includes docker scripts)
• minor improvements to docker scripts
• README files updated
• release notes added

How was this PR tested?

Two docker images were built and tested using the following commands:

docker build -f Dockerfile.O3DE --build-arg ROSCON_DEMO_BRANCH=jh/changes --build-arg ROSCON_DEMO_COMMIT=b00db96 -t roscon2023_demo/o3de:latest .

docker build -f Dockerfile.ROS --build-arg ROSCON_DEMO_BRANCH=jh/changes --build-arg ROSCON_DEMO_COMMIT=b00db96 -t roscon2023_demo/ros:latest .

[arturkamieniecki]

Overall these changes look good, but i think that the docker files need a little more changes. Instead of inputting the tag name in the commit argument but as the branch argument. I think this would create less confusion for readers of the readme.

[jhanca-robotecai]

@arturkamieniecki
Thank you for the valid suggestion of changing branch/commit order in the docker and for applying this suggestion. Do you agree with the overall changes in this PR?