docs: fix README TypeScript example for Microsoft.getAuth

[1ly4s0]

This update straightens out the “Standard Example (ESM)” snippet so newcomers can copy-paste it and launch the game without surprises.

What changed

• Pass client_id to the constructor – new Microsoft('<client_id>').
• Call getAuth('terminal') (or 'electron' | 'nwjs') instead of feeding it an object it can’t parse.
• Left every original comment and the rest of the code untouched so the diff is minimal and familiar.

Why

The previous sample looked fine at a glance but silently returned false, causing the launcher to run offline (or just error). This tweak matches the actual method signature and works out-of-the-box on Node 18+ / TS 5.

No library code changes, just docs.