update the readme with more information about what the mu-plugin does

README.md

@@ -5,14 +5,32 @@
 ![GitHub Release](https://img.shields.io/github/v/release/pantheon-systems/pantheon-mu-plugin)
 ![GitHub License](https://img.shields.io/github/license/pantheon-systems/pantheon-mu-plugin)
 
+The Pantheon Must-Use Plugin has been designed to tailor the WordPress CMS experience for Pantheon's platform.
 
-Workflow
---------
-Integrates WordPress with Pantheon Flow. Encourages updating plugins and themes in the Development environment and using Pantheon's git-based upstream core updates.
+What does that mean? We're glad you asked!
 
-Edge Cache
------------
-Facilitates communication between Pantheon's Edge Cache layer and WordPress. It allows you to set the default cache age, clear individual pages on demand, and it will automatically clear relevant urls when the site is updated. Authored by [Matthew Boynes](http://www.alleyinteractive.com/).
+## Workflow
+**Integrates WordPress with Pantheon Flow.** Encourages updating plugins and themes in the Development environment and using Pantheon's git-based upstream core updates. Alerts admins if an update is available but disables automatic updates (so those updates can be applied via the upstream).
 
-## Installation
-Install via Composer: `composer require pantheon-systems/pantheon-mu-plugin`.
+## Login
+**Customized login form.** The login page links back to the Pantheon dashboard on dev, test and live environments that do not have a domain attached.
+
+## Edge Cache
+**Facilitates communication between Pantheon's Edge Cache layer and WordPress.** It allows you to set the default cache age, clear individual pages on demand, and it will automatically clear relevant urls when the site is updated. Authored by [Matthew Boynes](http://www.alleyinteractive.com/).
+
+## WordPress Multisite Support
+**Simplifies multisite configuration.** The `WP_ALLOW_MULTISITE` is automatically defined on WordPress Multisite-based upstreams. The Network Setup pages and notices have been tailored to a Pantheon-specific WordPress multisite experience.
+
+## Maintenance Mode
+**Allows the site to be put into a maintenance mode.** Prevent users from accessing your sites during major updates by enabling Maintenance Mode either in the WordPress admin or via WP-CLI.
+
+## Installation via Composer
+**The Pantheon MU Plugin has been built to support Composer-based installs.** While Pantheon automation ensures that the latest version of the MU plugin are pushed with every update to WordPress, the Composer-based project ensures that you can manage it alongside your other WordPress mu-plugins, plugins and themes in your `composer.json`.
+
+```bash
+composer require pantheon-systems/pantheon-mu-plugin
+```
+
+Maintained by [Pantheon](https://pantheon.io) and built by the [community](https://github.com/pantheon-systems/pantheon-mu-plugin/graphs/contributors).
+
+[Releases and Changelogs](https://github.com/pantheon-systems/pantheon-mu-plugin/releases)