Merge pull request #18 from EmergeTools/telkins/README

Update README

README.md

@@ -12,24 +12,60 @@ fastlane add_plugin emerge
 
 ## About Emerge
 
-Fastlane plugin for Emerge
+[Emerge](https://emergetools.com) offers a suite of products to help optimize app size, performance and quality. This plugin provides a set of actions to interact with the Emerge API.
 
-## Run tests for this plugin
+## Usage
 
-To run both the tests, and code style validation, run
+To get started, first obtain an [API token](https://docs.emergetools.com/docs/uploading-basics#obtain-an-api-key) for your organization. The API Token is used to authenticate with the Emerge API in each call.
 
-```
-rake
-```
+```ruby
+# Your EMERGE_API_TOKEN is available on your Emerge profile page: https://www.emergetools.com/profile
+ENV['EMERGE_API_TOKEN'] = 'COPIED_FROM_EMERGETOOLS_PROFILE'
 
-To automatically fix many of the styling issues, use
+platform {:ios} do
+  lane :app_size do
+    emerge()
+  end
+end
 ```
-rubocop -a
+
+For a full list of available parameters run `fastlane action emerge`.
+
+## Git Configuration
+
+For build comparisons to work, Emerge needs the appropriate Git `sha` and `base_sha` values set on each build. Emerge will automatically compare a build at `sha` against the build we find matching the `base_sha` for a given application id. We also recommend setting `pr_number`, `branch`, and `repo_name` for the best experience.
+
+For example:
+
+- `sha`: `pr-branch-commit-1`
+- `base_sha`: `main-branch-commit-1`
+- `pr_number`: `42`
+- `branch`: `my-awesome-feature`
+- `repo_name`: `EmergeTools/hackernews`
+
+Will compare the size difference of your pull request changes.
+
+This plugin will automatically configure Git values for you assuming certain Github workflow triggers:
+
+```yaml
+on:
+  # Produce base builds with a 'sha' when commits are pushed to the main branch
+  push:
+    branches: [main]
+
+  # Produce branch comparison builds with `sha` and `base_sha` when commits are pushed
+  # to open pull requests
+  pull_request:
+    branches: [main]
+
+  ...
 ```
 
+If this doesn't cover your use-case, manually set the `sha` and `base_sha` values when calling the Emerge plugin.
+
 ## Issues and Feedback
 
-For any other issues and feedback about this plugin, please submit it to this repository.
+For any other issues and feedback about this plugin, please open a [GitHub issue](https://github.com/EmergeTools/fastlane-plugin-emerge/issues).
 
 ## Troubleshooting