Update README.

README.md

@@ -1,2 +1,26 @@
-# distance
+# Distance
 Distance helps you calculate the distance between GPS coordinates, in vanilla PHP. Pure and simple.
+
+## Installation
+
+### Using Composer
+
+When using [Composer](https://getcomposer.org) you can always load in the latest version.
+
+```bash
+{
+    "require": {
+        "ldebrouwer/distance": "dev-master"
+    }
+}
+```
+Check it out [on Packagist](https://packagist.org/packages/ldebrouwer/distance).
+
+## Documentation
+
+This is still on the to-do list. The code is pretty well documented though and should autocomplete in most IDEs.
+
+## Still to come
+- Haversine formula support.
+- Expanded unit support.
+- Documentation.