add some doc

PMB_README.md

@@ -0,0 +1,18 @@
+# ProtonMailBridge plus PostFix
+
+* GPG stores in-container are wildly insecure
+* This creates a volume for /root with these stores to preserve cache
+
+## Setup
+
+By default, `bridge` runs in non-interactive mode. You must set up the bridge initially.
+
+    docker-compose exec pmb bash
+    killall bridge
+    ./bridge -c
+
+When in cli mode, `login` will activate account.
+
+## msmtp test
+
+    echo "test" | msmtp -a pmb recipient@recipient.email

README.md

@@ -1,10 +1,14 @@
+# pmb-postfix
+
+## This is a merge of juanluisbaptiste/postfix and ProtonMail/proton-bridge
+
+See [PMB_README.md] integration readme.
+
 # docker-postfix
 [![Docker Build Status](https://img.shields.io/docker/cloud/build/juanluisbaptiste/postfix?style=flat-square)](https://hub.docker.com/r/juanluisbaptiste/postfix/builds/)
 [![Docker Stars](https://img.shields.io/docker/stars/juanluisbaptiste/postfix.svg?style=flat-square)](https://hub.docker.com/r/juanluisbaptiste/postfix/)
 [![Docker Pulls](https://img.shields.io/docker/pulls/juanluisbaptiste/postfix.svg?style=flat-square)](https://hub.docker.com/r/juanluisbaptiste/postfix/)
 
-## This is a merge of juanluisbaptiste/postfix and ProtonMail/proton-bridge
-
 Simple Postfix SMTP TLS relay [docker](http://www.docker.com) alpine based image with no local authentication enabled (to be run in a secure LAN).
 
 This image is available for the following architectures: