docs: add common issues markdown

These mostly pertain to the QEMU VM setup, so they might not be fully
relevant outside of VMs.

common-issues.md

@@ -0,0 +1,21 @@
+# Creating a new user
+1) Login to root account
+2) Type `useradd -m -G wheel -s /bin/bash <NAME>`
+3) Install `sudo` and `nvim`
+4) Type `EDITOR=nvim visudo`
+5) Uncomment the line `# %wheel ALL=(ALL:ALL) ALL`
+    - Towards the end of the file
+
+# Broken Internet Access on VM
+- This works for a VM with `enp1s0` link.
+```
+ip addr add 192.168.122.100/24 dev enp1s0
+ip route add default via 192.168.122.1
+echo "nameserver 8.8.8.8" > /etc/resolv.conf
+ping 8.8.8.8
+```
+- Then install dhcpcd
+```
+pacman -S dhcpcd
+systemctl enable --now dhcpcd@enp1s0
+```