Getting Started is incomplete, not at parity with RStan

[riddell-stan]

Getting Started is currently marked as a work in progress. https://pystan.readthedocs.io/en/latest/getting_started.html

We should match RStan's version: https://github.com/stan-dev/rstan/wiki/RStan-Getting-Started

We could also use translations. These seem like low-hanging:

• Spanish
• French
• Chinese Traditional Chars
• Chinese Simplified Chars
• Japanese
• Portuguese

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.