Add files directory, update readme

.gitignore

@@ -1,4 +1,5 @@
 .env.local
 config.yaml
-/files
+/files/*
+!/files/.gitkeep
 /target

README.md

@@ -38,7 +38,13 @@ psql -h localhost -p 5432 -U mitra mitra
 
 ### Run web service
 
-Create config file:
+Generate instance key:
+
+```
+cargo run --bin mitractl generate-rsa-key
+```
+
+Create config file, set `instance_rsa_key`, adjust other settings if needed:
 
 ```
 cp config.yaml.example config.yaml

src/config.rs

@@ -186,7 +186,7 @@ pub fn parse_config() -> Config {
         };
     };
     config.try_instance_url().expect("invalid instance URI");
-    config.try_instance_rsa_key().expect("invalid RSA private key");
+    config.try_instance_rsa_key().expect("invalid instance RSA key");
 
     config
 }