Alacritty's manual installation instructions take up a lot of space in
the README and they are hard to navigate because there's a lot of
information for specific distros which are irrelevant to most users.
To improve this situation, the manual installation section has been
moved to the `INSTALL.md` file. This allows keeping the readme to a
minimum which just includes the straight-forward instructions required
to install it on systems which provide packages for it.
Having a separate file also makes it possible to add a full index just
for the installation instructions, which makes it possible to skip
sections which are irrelevant.
Christian Duerr