Add package level documentation.

doc.go

@@ -0,0 +1,10 @@
+/*
+Fluux XMPP is a Go XMPP library, focusing on simplicity, simple automation, and IoT.
+
+The goal is to make simple to write simple adhoc XMPP clients:
+
+- For automation (like for example monitoring of an XMPP service),
+- For building connected "things" by plugging them on an XMPP server,
+- For writing simple chatbot to control a service or a thing.
+*/
+package xmpp