Add light colors in README

[Timokasse]

Let's not hide those in the dark of the code.

[wiggin15]

Hiding these colors from the documentation was intentional. Since they are not part of the standard, it is not recommended to use them, and using AnsiStyle.BRIGHT is a better idea. The EX colors are there more because we want colorama to know how to convert them to Windows API calls if they are used, but they should not really be used in the code. See #20.

I'm open to other opinions, though, if you still think it should be documented.

[Timokasse]

If there is a better way, I am all for it. But I tried and I don't see how I could do a
print(Fore.LIGHTRED_EX + 'some light red text')
with standard colors.

Also, I have specified that these colors are not part of the standard because I believe it is best to provide accurate information. And since it works on Linux and Cygwin (Windows) at least, I am convinced it could be useful to many.

[tartley]

Hey. FYI, yesterday I created a PR to test releases before we push them to PyPI. When that is merged, I'll be more confident about resuming merges and releases. I'll try to look at this PR soon. Thank you for creating it!

[Timokasse]

My commit is only updating the README. So there is not much chance it breaks something important anyway. ;-)