adding renderer for docs

view/mustache/doc/renderer.md

@@ -0,0 +1,15 @@
+@typedef {function(Object,Object.<String, function>):documentFragment} can.view.renderer(data,helpers) renderer
+
+@description A function returned by [can.view], [can.view.ejs], [can.view.mustache] that renders a 
+template into an html documentFragment.
+
+@param {Object} data An object of data used to render the template.
+
+@param {Object.<String, function>} helpers Local helper functions used by the template. 
+
+@return {documentFragment} A documentFragment that contains the HTML rendered by the template.
+
+@body
+
+A "renderer" function is a function returned by various [can.view] APIs that can be used
+to render data into a documentFragment.