createuser: add page

[almightyDavid]

• The page(s) are in the correct platform directories: common, linux, osx, windows, sunos, android, etc.
• The page(s) have at most 8 examples.
• The page description(s) have links to documentation or a homepage.
• The page(s) follow the content guidelines.
• The page(s) follow the style guide.
• The PR title conforms to the recommended templates.
• Version of the command being documented (if known): 17

[CLAassistant]

All committers have signed the CLA.

[Managor]

Thank you for your first contribution. Welcome to the project.