Update Group chat feature (design draft)

Group-chat-feature-(design-draft).md

@@ -1,4 +1,28 @@
-**!!Currently this patch is only a draft following our meetings!!**
+# Synospis
+
+The goal of this document is to describe how group chats (a.k.a. **swarm chat**) will be implemented in Jami.
+
+A *swarm* is a group able to discuss without any central authority in a resilient way. Indeed, if two person doesn't have any connectivity with the rest of the group (ie Internet outage) but they can contact each other (in a LAN for example or in a sub network), they will be able to send messages to each other and then, will be able to sync with the rest of the group when it's possible.
+
+So, the *swarm* is defined by:
+1. Ability to split and merge following the connectivity.
+2. Syncing of the hitory. Anyone must be able to send a message to the whole group.
+3. No central authority. Can't rely on any server.
+4. Non-repudiation. Devices must be able to verify old messages validity and to replay the whole history.
+5. PFS on the transport. Storage is managed by the device.
+
+# Scenarios
+
+## Create a Swarm
+
+*Bob wants to create a new swarm*
+
+**IN CONSTRUCTION**
+
+
+---------------
+
+**!! OLD DRAFT !!**
 
 Note: Following notes are not organized yet. Just some line of thoughts.