Explain configuration options in README.md

README.md

@@ -54,7 +54,79 @@ DIDs (sender, recipient) and some metainfo for the connection.
 ### Configuration
 
 Configuration is defined in [`config.json`](./config.json). The service tries to find the file in
-the working directory of the `svdx` process when it starts.
+the working directory of the `svdx` process when it starts. Below is an example config.json file with
+brief explanation of the sections and options:
+
+```json
+{
+  "http": {
+    "host": "",
+    "port": "8080",
+    "idleTimeout": "60s",
+    "readTimeout": "10s",
+    "writeTimeout": "10s"
+  },
+  "smtp": {
+    "host": "",
+    "port": "10025"
+  },
+  "smtpClient": {
+    "addr": "mailhog:1025",
+    "user": "",
+    "pass": "",
+    "hostname": "mail.example.com"
+  },
+  "didcomm": {
+    "did": "did:web:localhost%3A8080:svdx:v1:didcomm",
+    "serviceEndpoint": "https://localhost:8080/svdx/v1/didcomm/message",
+    "writeTimeout": "10s"
+  },
+  "db": {
+    "file": "didcomm.db"
+  },
+  "logLevel": "debug"
+}
+```
+
+##### `http` section
+
+Define the `svdx` web server configuration, its listening host and port and some timeouts.
+
+##### `smtp` section
+
+Define the `svdx` SMTP server configuration, where svdx will listen for incoming emails from postfix.
+
+##### `smtpClient` section
+
+Define the SMTP configuration of the postfix where the `svdx` must return emails for SMTP delivery.
+
+##### `didcomm` section
+
+Define the didcomm attributes of the `svdx` service.
+
+`did` specifies the DID of the `svdx`. It is created manually by using the public host of the service 
+and the path where the DID document is exposed. As an example, if the service is exposed at 
+`https://svdx-service.com` the DID of the service will be:
+```
+did:web:svdx-service.com:v1:didcomm
+```
+
+`serviceEndpoint` specifies the URL where the `svdx` accepts DIDComm messages. If we take the example
+above, the service endpoint must be:
+```
+https://svdx-service.com/v1/didcomm/message
+```
+
+`writeTimeout` specifies a timeout for sending DIDComm messages to other `svdx` instances.
+
+##### `db` section
+
+Define the filename of the sqlite database that will be used for storing DIDComm connections.
+
+##### `logLevel` section
+
+Define the logging level of the service. By default log level is `info`, but during development,
+deployment and debugging it should be set in the config to `debug`.
 
 ### Local development with Docker Compose