Review README.MD requirements and build/run instructions, and reorganize the document

[samaid]

1. I am not sure these instructions are still valid. At least those seem complicated. Need someone to go through instructions and checked if those are still valid.
2. Make it clear that Requirements are Build Requirements. Move all how-to-build stuff to the end.
3. In the beginning after Intro/Project description just provide simple Getting Started - how to get dpctl from conda/pip or from Intel Distribution for Python, how to run examples with installed package, how to run tests. Because all Google search for dpctl now goes to GitHub. Remember that your primary user targets are researchers who do not want to deal with build instructions.
4. All build stuff should be in the end for advanced users.