Add more info in README

README.md

@@ -7,7 +7,25 @@ run tmate on edge
 
 ## Why
 
-You may want a backdoor to access your edge servers
+You may want a backdoor to access your edge servers.
+Loosing control on an host can be as bad as loosing server itself.
+
+_tmate-edge_ aim to provide a way to always have a shell on hosts.
+
+As tmate host open connection to server, no need to configure NAT. Even if network change, it will reconnect to server.
+
+## How
+
+_tmate-edge_ is a _tmate_ client daemon.
+It connect itself to a tmate server which work like a "bastion".
+Connecting to the right session give you access to the right host.
+
+_tmate-edge_ is a snap package and can be deployed on any snap-ready OS.
+It's mainly designed for [Ubuntu Core](https://ubuntu.com/core).
+
+## Security considerations
+
+Use your own tmate server!
 
 ## Install