Polish Getting Started Docs

[priscilawebdev]

We've successfully migrated all the getting-started docs from sentry-docs to the main sentry repository, refer to the initiative [EPIC] Setup Docs Refactor for more details. However, there is still room for improvement. Here's a list of areas that need attention:

### Tasks
- [ ] https://github.com/getsentry/sentry/issues/53857
- [ ] https://github.com/getsentry/sentry/issues/53858
- [ ] https://github.com/getsentry/sentry/issues/53860
- [ ] https://github.com/getsentry/sentry/issues/53862
- [ ] https://github.com/getsentry/sentry/issues/53861
- [ ] https://github.com/getsentry/sentry/issues/54697
- [ ] https://github.com/getsentry/sentry/issues/55333
- [ ] https://github.com/getsentry/sentry/issues/56387
- [ ] https://github.com/getsentry/sentry/issues/54835
- [ ] https://github.com/getsentry/sentry/issues/56244