Directories within root after upgrading to MacOS Catalina (10.15)

After upgrading to MacOS Catalina, you would no longer be able to create directories in the root directory. On attempting to create a directory, you would see a “Read-only file system” error:

Nitins-MacBook-Pro:/ nitin$ sudo mkdir -p /data/db
Password:
mkdir: /data/db: Read-only file system
Nitins-MacBook-Pro:/ nitin$

Upon upgrading, directories existing within the root directory are moved to the path “/Users/Shared/Relocated Items/Security“ and a shortcut on the desktop named “Relocated Items” is created.

Also see: "Dedicated system volume" at https://www.apple.com/macos/catalina/features/