Reformat 'about' documentation for nextercism

[iHiD]

Hello. I'm trying to get all of the ABOUT.md files reformatted to fit with the new look and feel of nextercism. This means removing things like line-breaks and markdown that we're not supporting.

As an example from the C++ Track, we've gone from:

to:

As a general note, after these formatting changes get merged, we're hoping that track
maintainers will take some time to review the contents of the ABOUT.md file and edit
it to make it a bit shorter and more casual. We're looking for less wikipedia and more
of an enthusiastic and friendly pitch that you might make to a friend over a drink for
why they should try the language.

For some examples of tracks where I think they've done this well take a look at the
Go and R tracks:

• https://github.com/exercism/go/blob/master/docs/ABOUT.md
• https://github.com/exercism/r/blob/3f05539d19d7e20d2a9d5cd2cecd3dc56f4f23e8/docs/ABOUT.md

Thank you!