[Documentation] Correction for typo in collections.md on line 194

[csharpie]

Version info

Angular:
N/A

Firebase:
N/A

AngularFire:
N/A

Other (e.g. Ionic/Cordova, Node, browser, operating system):

How to reproduce these conditions

Failing test unit, Plunkr, or JSFiddle demonstrating the problem

Steps to set up and reproduce

Line 194 of ./docs/firestore/collections.md has a typo

export interface AccountDepoistId extends AccountDeposit { id: string; }

Sample data and security rules

Debug output

** Errors in the JavaScript console **

** Output from firebase.database().enableLogging(true); **

** Screenshots **

Expected behavior

Actual behavior

[csharpie]

PR was merged by maintainer. Closing issue.