Change apt-get to apt in Debian Installation Instruction #1840
Description
Summary
Change apt-get to apt to make the installation code readable and cleaner.
Details
I just realize this after submitting a PR #1838. Since the installation are using deb822 right now, I suggest we also change the apt-get to apt.
As you can read on Amazon article, apt become default package manager replacing apt-get. apt has a more features than apt-get, which in this case is terminal text color. This also makes the installation code more readable and cleaner, especially for beginners. This should be safe because apt was introduced on Debian 8 in 2014.
Sorry for not asking this earlier on #1833.