Update readme

README.md

@@ -1,4 +1,13 @@
-# Usage:
+# Backupinator
+
+A shell script running in a docker container that can be used for periodic backups.
+
+Everything mounted to `/in` is put into a `.tar.gz` file, encrypted with a 256 bit random key,
+which is in turn encrypted with the ssh public keys provided in `/keys`.
+
+A telegram bot can then be used to send the backup to one or multiple telegram chats.
+
+## Usage:
 ```
 docker build -t backupinator .
 
@@ -13,7 +22,7 @@ docker run \
     backupinator
 ```
 
-# Decryption
+## Decryption
 
 ```
 ./decrypt.sh ~/.ssh/id_rsa.pub key-you.enc backup.tar.gz.enc