chore: add CHANGELOG about 2.0.0

CHANGELOG.md

@@ -0,0 +1,10 @@
+# 2.0.0
+
+This release does not change the public interface to `cachios`, but does vastly change the build process and removes some polyfills.
+
+Because of this, I am releasing it as 2.0.0.
+
+It removes:
+- `export`, `import`, `let`, `const`
+- eslint, but the project still adheres to `eslint-config-airbnb`
+- `babel-runtime` - this could affect browser compatibility, but it "shouldn't". [Axios already requires promises to be natively supported (it does not polyfill them) and that is the only "new JS" we use](https://github.com/axios/axios#promises).