docs: Add 8.0.0 breaking change note

Author: jooohhn

CHANGELOG.md

@@ -1,8 +1,9 @@
 # [8.0.0](https://github.com/amplitude/amplitude-javascript/compare/v7.4.4...v8.0.0) (2021-03-15)
 
-
 ### Bug Fixes
 
+Removed support for React Native. We recently released an entirely new SDK focused entirely on React Native support, this can be found at https://github.com/amplitude/Amplitude-ReactNative. We will be writing a migration guide for users looking to move to the new React Native SDK.
+
 * call onError in init function ([#368](https://github.com/amplitude/amplitude-javascript/issues/368)) ([d2ae868](https://github.com/amplitude/amplitude-javascript/commit/d2ae8686752d4a977213f1c0b9e2fe61ba24863c))
 * remove callback from argument to function that takes no arguments ([#370](https://github.com/amplitude/amplitude-javascript/issues/370)) ([777dead](https://github.com/amplitude/amplitude-javascript/commit/777dead4a5051e8d4d7e990aeb365b8d868e9383))