[docs] patch examples and add a no fuss quickstart snippet

[0o-de-lally]

Does your PR solve an issue?

Newcomers struggle a bit with getting the project setup with proper features for the test harness.

• Added the necessary * for dereferences
• Created a TL;DR using a zero config Sqlite example

perhaps fixes https://github.com/launchbadge/sqlx/issues/2368