feat: #11 update README

README.md

@@ -2,15 +2,48 @@
 
 A little web server providing JWT token for auth auser.
 
-**NOTE**: for now, the server is listening on port **9000**. Change it, in the src if needed.
-
 ## Build
-
 ```bash
 cargo build --release
+```
 
-# run the server
-./target/release/simple-auth
+## Configuration
+
+### Store
+The store represents the credentials. For now, this a `.txt` file with plain passwords. You have to create one like:
+```txt
+# acts as a comment (only on a start line)
+<username>:<password>
+```
+**WARN**: the file should have a chmod to **600**.
+
+### RSA key pair creation
+The server uses **RS384** signature algorithm (asymmetric). You have to create a private key to sign the token and a public key for the validation:
+```bash
+openssl genrsa -out priv.pem 2048
+openssl rsa -in priv.pem -outform PEM -pubout -out pub.pem
+```
+**WARN**: those files must be readable be the server user
+
+### INI file
+To start the server correctly, you need to create an `.ini` file as below:
+```ini
+[server]
+url = <ip>:<port>
+
+[store]
+path = <store_path>
+
+[jwt]
+issuer = <issuer.fr>
+private_key = <priv_key_path> 
+public_key = <pub_key_path>
+expiration_time = 2 # in hours
+```
+
+## Run
+```bash
+./simple-auth <ini_path>
 ```
 
 ## Test