TASK: Add some documentation about resource proxies

README.md

@@ -9,6 +9,7 @@ section of your composer.json**.
 
 * Wilhelm Behncke - [email protected]
 * Martin Ficzel - [email protected]
+* ... and others
 
 *The development and the public-releases of this package is generously sponsored by our employer https://www.sitegeist.de.*
 
@@ -108,6 +109,15 @@ the commands.**
 ```
 **Note:** Use this command on a regular basis, because your stash tends to grow **very** large.
 
+## Resource proxies
+
+While cloning the database to your local dev system is manageable even for larger projects, downloading all the assets is often not an option.
+
+For this case the package offers the concept of resource proxies. Once activated, only the resources that are actually used are downloaded just at the moment they are rendered.
+This is done by custom implementations of `WritableFileSystemStorage` and `ProxyAwareFileSystemSymlinkTarget` and works out of the box if you use this storage and target in you local development environment.
+If you use other local storages, for example a local S3 storage, you can easily build your own proxy aware versions implementing the interfaces `ProxyAwareStorageInterface` and `ProxyAwareTargetInterface`of this package.
+
+
 ## Installation
 
 Sitegeist.Magicwand is available via packagist. Just add `"sitegeist/magicwand" : "~1.0"` to the require-dev section of the composer.json or run `composer require --dev sitegeist/magicwand`. We use semantic-versioning so every breaking change will increase the major-version number.