add babel-helper-fixtures usage

packages/babel-helper-fixtures/README.md

@@ -1 +1,31 @@
 # babel-helper-fixtures
+
+## Usage
+
+```javascript
+import { get as getFixtures } from "babel-helper-fixtures";
+
+type TestFile = {
+  loc: string;
+  code: string;
+  filename: string;
+};
+
+type Test = {
+  title: string;
+  disabled: boolean;
+  options: Object;
+  exec: TestFile;
+  actual: TestFile;
+  expected: TestFile;
+};
+
+type Suite = {
+  options: Object;
+  tests: Array<Test>;
+  title: string;
+  filename: string;
+};
+
+let fixtures: Array<Suite> = getFixtures("/User/sebmck/Projects/babel-something/test/fixtures");
+```