DOCS Update readme with installation instructions and basic usage

README.md

@@ -8,13 +8,52 @@
 
 ## Introduction
 
-Adds a new form element for SilverStripe Elemental. This block allows users to
-construct User Forms using the SilverStripe UserForms module.
+This module integrates [silverstripe/silverstripe-userforms](https://github.com/silverstripe/silverstripe-userforms)
+into [dnadesign/silverstripe-elemental](https://github.com/dnadesign/silverstripe-elemental) and provides a new
+content block called "Form", which can be used to create user defined forms.
+
+## Requirements
+
+* SilverStripe ^4.0
+* Elemental ^2.0
+* UserForms ^5.0
 
 ## Installation
 
+Install with Composer:
+
 ```
 composer require dnadesign/silverstripe-elemental-userforms 1.x-dev
 ```
 
+Ensure you run `dev/build?flush=1` to build your database and flush your cache.
+
+## Usage
+
+Once installed, you will see a "Form" option when adding a new element to a page:
+
+![Adding a Form element in the CMS](docs/images/adding-form.png)
+
+From here, editing the form is the same as using the UserForms module normally. Please refer to the
+[UserForms module documentation](https://github.com/silverstripe/silverstripe-userforms) for more information.
+
+## Applying the ElementalPageExtension
+
+Note that if you apply the ElementalPageExtension to a high-level class like SiteTree or Page, the default
+UserDefinedForm page from the UserForms module will also be available in your CMS. This can be confusing to a user,
+especially if you can add a Form to a UserDefinedForm page which already has everything it needs from the UserForms
+module by default.
+
+There are valid use cases where this might be what you want (or variations of it), however we would recommend
+applying the ElementalPageExtension to subclasses of Page and excluding the UserDefinedForm class from this
+extension to avoid this situation from happening.
+
+## Versioning
+
+This library follows [Semver](http://semver.org). According to Semver, you will be able to upgrade to any minor or patch version of this library without any breaking changes to the public API. Semver also requires that we clearly define the public API for this library.
+
+All methods, with `public` visibility, are part of the public API. All other methods are not part of the public API. Where possible, we'll try to keep `protected` methods backwards-compatible in minor/patch versions, but if you're overriding methods then please test your work before upgrading.
+
+## Reporting Issues
 
+Please [create an issue](https://github.com/dnadesign/silverstripe-elemental/issues) for any bugs you've found.