Update README.

README.md

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-> THIS IS AN EXPERIMENTAL BRANCH WHICH ADDS SUPPORT FOR PROCESS GROUPS. 
 
 # Syn
 **Syn** (short for _synonym_) is a global Process Registry and Process Group manager for Erlang.
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 ## Introduction
 
 ##### What is a Process Registry?
-A global Process Registry allows to register a process on all the nodes of a cluster with a single Key. Consider this the process equivalent of a DNS server: in the same way you can retrieve an IP address from a domain name, you can retrieve a process from its Key. 
+A global Process Registry allows to register a process on all the nodes of a cluster with a single Key. Consider this the process equivalent of a DNS server: in the same way you can retrieve an IP address from a domain name, you can retrieve a process from its Key.
+
+Typical Use Case: registering on a system a process that handles a physical device (using its serial number).
 
 ##### What is a Process Group?
 A global Process Group is a named group which contains many processes, eventually running on different nodes. With the group Name, you can retrieve on any cluster node the list of these processes, or publish a message to all of them. This mechanism allows for Publish / Subscribe patterns.
 
+Typical Use Case: a chatroom .
+
 ##### What is Syn?
 Syn is both. It's a Process Registry and Process Group manager that has the following features:
 
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 	Error = pid_already_in_group
 ```
 
+> When a process joins a group, Syn will automatically monitor it.
+
 To remove a process from a group:
 
 ```erlang