Add documentation and license

README.md

@@ -1,2 +1,32 @@
 # Friendica Global Directory
 
+This standalone software is meant to provide a global public directory of [Friendica ](https://github.com/friendica/friendica) profiles across nodes.
+
+This is an opt-in directory, meaning that each node can choose not to submit its profiles to global directories, and each user can individually choose not to be submitted.
+
+## Requirements
+
+- PHP >= 7.1 with:
+    - Curl
+    - GD
+    - JSON
+- Command-line access
+- A web server with URL rewriting (Apache)
+- A database server (MariaDB)
+- A background task scheduler (Crontab)
+- About 60 MB for a Git install
+- About 100 MB for a full database
+
+## Installation
+
+Please refer to the provided [installation instructions](INSTALL.md).
+
+## See also
+
+- [Project Concepts](docs/Concepts.md)
+- [Directory Protocol](docs/Protocol.md)
+
+## Special thanks
+
+- [Beanow](https://github.com/Beanow) for his efforts to spearhead the previous version of the Friendica Directory software.
+- [Scott Arciszewski](https://github.com/paragonie-scott) for his inspiration to use Slim and his invaluable Slim app example.