[docs] introduce Expo package API reference page

[Simek]

Why

So far, we have only exposed the docs for one exported method from main expo which was registerRootComponent.

Also fixes ENG-12111

How

This PR adds the page including the methods and types exported from main expo package. In the future, it should be the great place for exposing more common code shared between the packages like PermissionsResponse, Subscription or other common elements which we re-export in package code from the dependencies.

I have also removed the registerRootComponent to avoid listing the same information twice. The changes have been only applied to unversioned docs.

Test Plan

The changes have been reviewed locally. ALl lint checks and tests are passing.

Preview

[expo-bot]

The Pull Request introduced fingerprint changes against the base commit: 9ae1cb6

Fingerprint diff

[
  {
    "type": "dir",
    "filePath": "../../node_modules/expo",
    "reasons": [
      "bareRncliAutolinking"
    ],
    "hash": "380d87060ef549a5b26c0cb313192f296230e574"
  },
  {
    "type": "dir",
    "filePath": "../../packages/expo",
    "reasons": [
      "expoAutolinkingIos",
      "expoAutolinkingAndroid",
      "expoConfigPlugins",
      "expoConfigPlugins"
    ],
    "hash": "c7873af682994bd9687e08e7ca584adf565ab983"
  },
  {
    "type": "dir",
    "filePath": "../../packages/expo-modules-core",
    "reasons": [
      "expoAutolinkingIos",
      "expoAutolinkingAndroid"
    ],
    "hash": "b6675d89e48b2a5933a3f5100a1fc35cca27204c"
  }
]

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⚠️ Suggestion: Missing changelog entries

Your changes should be noted in the changelog. Read Updating Changelogs guide and consider adding an appropriate entry to the following changelogs:

• packages/expo-modules-core/CHANGELOG.md
• packages/expo/CHANGELOG.md

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[linear]

ENG-12111 Create docs for the `expo` package

[Kudo]

that's great one. thanks for bringing this doc.