docs: fixed the typos in the readme.md file

Author: alkavats1

README.md

@@ -85,7 +85,7 @@ AngularFire doesn't follow Angular's versioning as Firebase also has breaking ch
 
 ### Polyfills
 
-Neither AngularFire or Firebase ship with polyfills. To have compatability across as wide-range of environments we suggest the following polyfills be added to your application:
+Neither AngularFire nor Firebase ship with polyfills. To have compatability across as wide-range of environments we suggest the following polyfills be added to your application:
 
 | API | Environments | Suggested Polyfill | License |
 |-----|--------------|--------------------|---------|
@@ -120,7 +120,7 @@ Get help on our [Q&A board](https://github.com/angular/angularfire/discussions?d
 
 ## Developer Guide
 
-This developer guide assimes you're using the new tree-shakable AngularFire API, [if you're looking for the compatability API you can find the documentation here](docs/compat.md).
+This developer guide assumes you're using the new tree-shakable AngularFire API, [if you're looking for the compatability API you can find the documentation here](docs/compat.md).
 
 [See the v7 upgrade guide for more information on this change.](docs/version-7-upgrade.md).