Improve READMEs of each folder

[mateosss]

Matter folder structure is more or less preserved on install even though some folders don't have more than a README file. The idea behind this is that a curious user or potential contributors can read right from the repo what each folder is supposed to contain and get an idea of how Matter works in the process.

If you've been reading the project and think you can improve the description of some area that you found particularly weird, go ahead and submit a PR, hopefully it will make it easier for future readers.

[Niaz-Ul-Haque]

I think having "Uninstall" early on is not a good idea. If it's at the end of the Usage category, it will be better. If it's at the last, even better. And I can also see that there is a total of 9 examples, I think it's too many examples and people who rush through the readme (most people) will probably go till 4 - 5 examples max.

If you think I am making some sense, please do assign me this issue and I'll try to make it better as much as possible from my side.

(These are just my opinions and what I think of the readme.)

Thank you!