docs: add description, usage, and configuration to readme

README.md

@@ -1,2 +1,30 @@
 # shy-launcher
-Utility for launching apps for Linux.
+
+**shy-launcher** is an utility for downloading assets and launching applications on Linux.
+
+## What can it do?
+It can:
+- Download assets over HTTP/S before the program starts
+- Verify that you have the latest version of your files/program/plugins
+- Change permissions for executable downloads
+
+## Configuration
+
+Below is an example `config.json`; adapt it to your needs:
+
+```json
+{
+    "name": "My Java server",
+    "run": "java",
+    "args": ["-jar", "server.jar"],
+    "downloads": [{
+        "method": "GET",
+        "url": "https://some.asset.server.shiewk.de/coolserver/latest/server.jar",
+        "headers": {
+            "Authorization": "Bearer tOk3n"
+        },
+        "filename": "server.jar",
+        "permissions": 700
+    }]
+}
+```