[docs][Expo config] Fix Constants.manifest reference and update verbiage

[amandeepmittal]

Why

Refs ENG-6588

How

• By updating the reference of Constants.manifest to Constants.expoConfig.
• Also, added a note for SDK 45 and below to use Constants.manifest.
• updated the overall verbiage, did some re-organization of text and added Callout components for blockquotes.
• Update link text in https://docs.expo.dev/versions/latest/config/app/ referring back to the Configuration with app.json / app.config.js page. Also, backported to SDK 45, 44, & 43.

Test Plan

Run docs locally via yarn dev and then go open http://localhost:3002/workflow/configuration/.

Checklist

• Documentation is up to date to reflect these changes (eg: https://docs.expo.dev and README.md).
• Conforms with the Documentation Writing Style Guide
• This diff will work correctly for expo prebuild & EAS Build (eg: updated a module plugin).

[linear]

ENG-6588 Update example in /workflow/configuration

Link: https://docs.expo.dev/workflow/configuration/#dynamic-configuration-with-appconfigjs

The example Constants.manifest.extra.fact === 'kittens are cool'; is outdated. Should be using expoConfig and mention a note about SDK 45 or below.

[Simek]

LGTM, thank for the updates!