Add notes/questions on the Fetch Vector Data section

Minimal-Vector-API.md

@@ -22,6 +22,37 @@ var layer = new ol.layer.Vector({
 
 For data that is already available in memory as string or object, a `data` option can be provided instead of `url`.
 
+Notes and questions from @elemoine:
+
+So ol.layer.Vector works with a fixed strategy, an HTTP protocol, and a GeoJSON format (using ol2 terms here). What would the API look like if what I want to use is a fixed strategy and, say, a WFS protocol?
+
+What do we fix in a source type? The strategy? The protocol? Both? I think I would fix the strategy, and get rid of strategies entirely in ol3.
+
+So:
+
+```js
+var layer = new ol.layer.Vector({
+  style: myStyle,
+  source: new ol.source.VectorFixed({
+    protocol: new ol.protocol.WFS({
+      url: 'http://example.com/data',
+      parser: new ol.parser.GeoJSON()
+    })
+  })
+});
+```
+
+For Fixed/HTTP/GeoJSON, Fixed/HTTP/TopoJSON, and Fixed/HTTP/KML we can certainly provide convenience classes: ol.source.GeoJSON, ol.source.TopoJSON, and ol.source.KML. E.g.
+
+```js
+var layer = new ol.layer.Vector({
+  style: myStyle,
+  source: new ol.source.GeoJSON({
+    url: 'http://example.com/data'
+  })
+});
+```
+
 ## Style Vector Data
 
 Initially, we can style data with a subset of CartoCSS or SLD, without exposing a style API.