While the above works in any GNU/Linux installation where everything (except perhaps /home) lives on the root partition, I would add a “Step 2.1” to your instructions for when this is not the case ─ and this is a scenario where the manjaro-chroot tool would fail just as well. 
To give you an example, I always install my GNU/Linux distributions the tried and tested UNIX way. I’ll illustrate what I mean with a df listing of the partitions on my own system here.
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 511M 544K 511M 1% /boot/efi
/dev/sda2 488M 63M 390M 14% /boot
/dev/sda3 1.0G 26M 767M 4% /
/dev/sda4 22G 6.5G 15G 31% /usr
/dev/sda5 512M 3.4M 499M 1% /usr/local
/dev/sda6 2.0G 101M 1.7G 6% /opt
/dev/sda8 400G 72G 328G 18% /srv
/dev/sda9 450G 2.8G 446G 1% /home
/dev/sda11 20G 3.2G 17G 16% /var
As you can see, the above layout would require a few extra steps, depending on what exactly the reason is why you’re chrooting into your installed system.