[firebase-release] Removed change log and reset repo after 2.1.0 release (#158)

* [firebase-release] Removed change log and reset repo after 2.1.0 release

* Update changelog.txt

* Create changelog.txt

* Create changelog.txt

Author: bojeil-google

changelog.txt

@@ -1,7 +1 @@
-feature - Added support for OAuth providers in a Cordova environment.
-feature - Added support for passing custom OAuth parameters to OAuth providers.
-feature - Added phone code resending countdown to phone code entry page.
-feature - Added terms of service for phone sign-in pages.
-feature - Ability to auto populate the country code from the national number.
-feature - Added support for selecting the default country for phone authentication.
-fixed - Skip NASCAR screen when only phone provider is enabled and render phone sign in screen directly.
+