Adding documentation to the README for import errors in vim (#1317)

* Adding documentation to the README for import errors in vim

I had the same issue as psf/black#1148 and have been searching for a
solution to this. I realized that you cannot fix it by change anything
in the code, but by re-compiling the C extensions of regex and
typed-ast. Installing this packages from the tarballs solves the
problem.

* Fixing a bad copy&paste

Co-Authored-By: Hugo van Kemenade <hugovk@users.noreply.github.com>

* chore: changed made by pre-commit

* chore: better way of dealing with non-binary installs

* chore: adding vim cache files to the ignore list

Co-authored-by: Hugo van Kemenade <hugovk@users.noreply.github.com>