clearer selectors

D3.md

@@ -5,8 +5,8 @@
 ### Selection
 
 ```javascript
-d3.select('css selector') //like document.querySelector()
+d3.select('#some-id') //like document.querySelector()
-d3.selectAll() //like document.querySelectorAll()
+d3.selectAll('.some-class') //like document.querySelectorAll()
 d3.select('main').selectAll('span'); //can chain to select ancestors
 ```