update component and qweb doc

doc/qweb.md

@@ -1,3 +1,27 @@
 # QWeb
 
-hey
+QWeb is a template specification. The QWeb class in this repository is:
+
+- an implementation of the QWeb specification
+- which outputs a virtual dom instead of a string
+- and extended with a few extra directives
+
+## QWeb Specification
+
+add here a full description of what QWeb is supposed to be, with some examples
+
+## QWeb Implementation
+
+```javascript
+var qweb = new QWeb();
+qweb.addTemplate("sometemplate", '<div>hello <t t-esc="name"/></div>');
+
+// result is a vnode which represent <div>hello world</div>
+result = qweb.render("sometemplate", { name: "world" });
+```
+
+## QWeb extensions
+
+- t-on directive
+- t-widget, t-props, t-key
+- t-ref