Instructions to link runtime on Linux/macOS can have a bad result

[rseymour]

The docs recommend the command:

ln -s $PWD/runtime ~/.config/helix/runtime

Which works if and only if you don't already have a ~/.config/helix/runtime So for folks going from a package install to a source install, they get an automatically broken runtime directory. ie they'll end up with something like:

~/.config/helix/runtime/runtime

This can be fixed with something like:
ln -Ts $PWD/runtime ~/.config/helix/runtime which fails if ~/.config/helix/runtime already exists, at which point the user could delete it or something.