[docs] Add banner for App.js Conf (#6074)
[docs] Add banner for App.js Conf (#6074)

# How

Based on https://github.com/expo/universe/commit/0b1c1c86d8650968566a676eee338a77e280e847 and  https://github.com/expo/universe/commit/fb2b029b3a0503ac6b766824b008619496c6f63b

# Test Plan

N/D

exponentjs/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent,exponent/exponent,exponentjs/exponent,exponent/exponent,exponentjs/exponent