Update the Readme

[lionelkusch]

This is an update of the readme.
For see the result, follow this link: https://github.com/lionelkusch/hidimstat/tree/PR_README.txt

For updating the README, I get inspiration from the following repository:

• nilearn: https://github.com/nilearn/nilearn/blob/main/README.rst
• skrub: https://github.com/skrub-data/skrub/blob/main/README.rst
• scikitlearn: https://github.com/scikit-learn/scikit-learn/blob/main/README.rst
• brian2: https://github.com/brian-team/brian2/blob/master/README.md
• nest simulator: https://github.com/nest/nest-simulator/blob/master/README.md
• moabb: https://github.com/NeuroTechX/moabb/blob/develop/README.md

[jpaillard]

I have a personal preference for a more streamlined Readme (see skrub for instance).
But please feel free to ignore my comments if you like a more thorough one.

[jpaillard]

This badge does not render well

[lionelkusch]

It's normal because the name of the workflow is not yet modified.
It will be done with this PR.

[bthirion]

LGTM, thx.