update readme

Author: tylerturdenpants

README.md

@@ -1,29 +1,83 @@
 # ember-codemods-telemetry-helpers
 
-[![Build Status](https://travis-ci.com/ember-codemods/ember-codemods-telemetry-helpers.svg?branch=master)](https://travis-ci.com/ember-codemods/ember-codemods-telemetry-helpers)
+[![Build Status](https://travis-ci.com/ember-codemods/ember-codemods-telemetry-helpers.svg?branch=master)](https://travis-ci.com/ember-codemods/ember-codemods-telemetry-helpers) [![npm](https://img.shields.io/npm/v/ember-codemods-telemetry-helpers.svg?label=npm)](https://www.npmjs.com/package/ember-codemods-temetry-helpers)
 
-[![npm](https://img.shields.io/npm/v/ember-codemods-telemetry-helpers.svg?label=npm)](https://www.npmjs.com/package/ember-codemods-temetry-helpers)
 
-Telemetry helpers runs the app, grabs basic info about all of the modules at runtime. 
+Telemetry helpers runs the app, grabs basic info about all of the modules at runtime.
 This allows the codemod to know the names of every helper, component, route, controller, etc in the app without guessing / relying on static analysis.
 They basically help you to create "runtime assisted codemods".
 
 ## Goal
 The goal of the project though was to enable each codemod to manage its own type of data gathering
 and that the gather-telemetry-helpers package provides the harness to run that custom gathering function
 
+## Usage
+
+Assuming you are authoring a codemod with [codemod-cli](https://github.com/rwjblue/codemod-cli), `ember-codemods-telemetry-helpers` allows you freedom to assign your own "telemetry gathering" function while provide one of its own out of the box (opt-in).
+
+```javascript
+#!/usr/bin/env node
+'use strict';
+
+const { gatherTelemetryForUrl } = require('ember-codemods-telemetry-helpers');
+const appLocation = process.argv[2];
+const args = process.argv.slice(3);
+
+// Gather only helpers
+function findHelpers(possibleEmberObject) {
+  if (
+    possibleEmberObject &&
+    possibleEmberObject.default &&
+    possibleEmberObject.default.isHelperFactory
+  ) {
+    return true;
+  }
+}
+
+
+(async () => {
+  await gatherTelemetryForUrl(appLocation, findHelpers);
+
+  require('codemod-cli').runTransform(__dirname, 'my-cool-transform', args, 'hbs');
+})();
+```
+
+All invocations of `gatherTelemetryForUrl` internally returns an object enumerated with properties named after all possible entries within `window.require.entries`.  The values of each property is the value returned from within the gathering function.  Usuing the example above, the output might be (for example):
+
+```javascript
+{
+  'ember-inflector/lib/helpers/pluralize': true,
+  'ember-inflector/lib/helpers/singularize': true,
+  'input/helpers/app-version': true,
+  'input/helpers/pluralize': true,
+  'input/helpers/singularize': true,
+}
+
+```
+## Contributing
+
+### Installation
+
+* clone the repo
+* change into the repo directory
+* `yarn`
+
+### Running tests
+
+* `yarn test`
+
 ## More info
 
-See "Gathering runtime data" section of 
+See "Gathering runtime data" section of
 https://github.com/ember-codemods/ember-native-class-codemod#gathering-runtime-data for some additonal info
 
 
-This project was extracted from (ember-native-class-codemod)(https://github.com/ember-codemods/ember-native-class-codemod). 
-That codemod uses (puppeteer)(https://github.com/GoogleChrome/puppeteer) (via this lib) to visit the Ember app and gather telemetry necessary to convert to native classes. 
+This project was extracted from (ember-native-class-codemod)(https://github.com/ember-codemods/ember-native-class-codemod).
+That codemod uses (puppeteer)(https://github.com/GoogleChrome/puppeteer) (via this lib) to visit the Ember app and gather telemetry necessary to convert to native classes.
 
-The idea for the extraction was to put the harness in this package 
-(extracted from the native class codemod), but have the actual "telemetry gathering" 
+The idea for the extraction was to put the harness in this package
+(extracted from the native class codemod), but have the actual "telemetry gathering"
 live in each individual codemod project because the things that they need are quite different
-for example, for [implicit this codemod](https://github.com/ember-codemods/ember-no-implicit-this-codemod) and 
+for example, for [implicit this codemod](https://github.com/ember-codemods/ember-no-implicit-this-codemod) and
 [angle brackets codemod](https://github.com/ember-codemods/ember-angle-brackets-codemod) all we need to know is an array of the helpers and components in the app
 but for [native class codemod](https://github.com/ember-codemods/ember-native-class-codemod) it needs much more info (names and types of methods, properties, etc on each default export)