[EPIC] Docs

[cspotcode]

Docs aren't fun, so I'm creating an epic to track all docs tasks in one place.

Some of these items came from the TODO list on #1297. I'd spent too long on #1297, so I wanted to merge it as-is and tackle these items in the future.

• [ ] Refer to CommonJS / ESM consistently across all docs; link to common page explaining the difference

  • CommonJS
  • Native ECMAScript modules
  • ESM
  • native ESM

• [x] Refer to ts-node consistently; naming is inconsistent throughout the readme (implemented in #1481)

  • TypeScript Node
  • TS Node
  • ts-node
  • ts-node (in backticks)

• [x] remove "under construction" banner

• [ ] Additions to "Troubleshooting" page

  • [x] #1607
  • [ ] Common troubleshooting tricks?

• [x] Revisit "shebang" (implemented by #1682)

  • move to "advanced?"
  • deduplicate with "usage"
  • explain shebang gotchas
  • consider keeping as discussion thread?

• [x] add "API" page to "Advanced" section (implemented by #1682)

  • list cool things you can do with the API
    • create a custom REPL
    • simpler TS compiler wrapper
    • detect if ts-node is already installed via process.

• [x] #1499

• [x] #1456

• [ ] #1089

• [x] #1506

• [x] #1606

• [x] #1670

• [ ] #1674

• [ ] #1675