Doc: Linux installation method only supports APT #664

Hi everyone,

I was trying to install devtunnel CLI in my Fedora box using the installation instructions from the docs and received an error that apt-get is not available. It seems like the script assumes Debian based distributions and doesn't state that in the docs.

› curl -sL https://aka.ms/DevTunnelCliInstall | bash
Downloading the devtunnel CLI...
sudo: apt-get: command not found

The script should support yum or dnf or RHEL based distributions and probably fallback to downloading the binary and placing it somewhere at $PATH, /usr/local/bin, or the user's ~/.local/bin path.