Updated readme and docker port

Dockerfile

@@ -1,6 +1,5 @@
 FROM alpine:latest
 COPY mailspy /app/mailspy
-EXPOSE 8089
 WORKDIR app
 EXPOSE 7777
 EXPOSE 7778

README.org

@@ -10,7 +10,7 @@ Mailspy is available in binary distribution for 64-bit linux systems.
 curl https://objects.5sigma.io/public/mailspy.tar.gz | tar -xz 
 #+end_src
 
-* Usage
+* Binary usage
 
 Execute the mailspy binary:
 
@@ -37,6 +37,14 @@ http://localhost:7777
 - The HTTP port for the web interface can be configured with -h <port> 
 
 
+* Docker
+
+Mailspy is avialable as a Docker image. To run it as a temporary container use:
+
+#+begin_src sh
+docker run --rm  -p 7777:7777 -p 7778:7778 git.5sigma.io/mailspy/mailspy:latest
+#+end_src
+
 * Development
 
 The core application Rust application is located in /src folder. This contains both the SMTP and HTTP servers. The web interface is located in /ui and is a Svelte application.