[docs] Add 'Star Us on GitHub' link like on the website (#23981)

# Why

We decided to follow what we are doing on the website and add a 'Star Us
on GitHub' link.

# How

By adding a button li

[docs] Add 'Star Us on GitHub' link like on the website (#23981)

# Why

We decided to follow what we are doing on the website and add a 'Star Us
on GitHub' link.

# How

By adding a button like on the website.

I added a similar button which just links to the GitHub page, so it's a
bit redundant with current GitHub link (do we want to change URL to
something more specific? I am not sure if it makes sense to replace the
existing GitHub link as people want to go there even if they already
starred us and it feels incorrect to use this button for that).

Button is displayed on only desktop browser size (not enough space on
mobile and if we were to replace it with icon it would directly
duplicate the existing link).

# Test Plan

\-

# Checklist

- [x] Documentation is up to date to reflect these changes (eg:
https://docs.expo.dev and README.md).
- [x] Conforms with the [Documentation Writing Style
Guide](https://github.com/expo/expo/blob/main/guides/Expo%20Documentation%20Writing%20Style%20Guide.md)
- [x] This diff will work correctly for `npx expo prebuild` & EAS Build
(eg: updated a module plugin).

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