Document basic CLI usage examples

[alhassy]

Is your feature request related to a problem? Please describe.

At first glance, juvix --help shows the option --stdin which is documented to Read from Stdin, and so I thought I could use this to obtain an interactive REPL.

• Sadly this is not the case since a compiler command is also required.
• It would have been nice to see an example usage of the CLI's options.

Describe the solution you'd like

It would be useful to provide example usage for the various options of the Juvix CLI.

• E.g., Haskell's GHCI and NodeJS CLI have tldr support, as shown below, and it would be nice if Juvix has this as well.

Additional context This issue was caused by #1485

[paulcadman]

Having concrete usage examples for the Juvix CLI is a great idea. We will add a page for this to our documentation and link it from the README. We will consider submitting a page to tldr when the Juvix CLI is stable.