Doc fix on Firebase setup

[gregackerman]

On the Firebase instructions, I believe steps 3 and 4 are mutually exclusive, only needing to provide app name and package name once, not twice. Maybe keep step 4 to indicate this is the package name for your mobile app? Thanks for checking this.

[dimayuga]

Hi @vishalpalliyathu, can you please take a look at @gregackerman's comment, and update the docs in both staging and prod as necessary? Thanks!