more README updates

Author: callmecavs

README.md

@@ -37,10 +37,10 @@ import jump from 'jump.js'
 
 ### Call
 
-Jump exports a _singleton_, so there's no need to create an instance. Just call it, passing in a [target](#target).
+Jump exports a _singleton_, so there's no need to create an instance. Just call it, passing a [target](#target).
 
 ```es6
-// call Jump
+// call Jump, passing a target
 
 jump('.target')
 ```
@@ -49,11 +49,9 @@ Note that the singleton can make an infinite number of jumps.
 
 ## Options
 
-All options, **except [target](#target)**, are optional, and have sensible defaults. Default options are shown below.
+All options, **except [target](#target)**, are optional, and have sensible defaults. The defaults are shown below:
 
 ```es6
-// default options
-
 jump('.target', {
   duration: 1000,
   offset: 0,
@@ -86,19 +84,22 @@ jump(100)
 jump(-100)
 ```
 
-Or, scroll _to an element_ by passing a node or a selector.
+Or, scroll _to an element_, by passing either:
+
+* a node, or
+* a CSS selector
 
 ```es6
 // passing a node
 
-const node = document.querySelector('#target')
+const node = document.querySelector('.target')
 
 jump(node)
 
-// passing a selector
-// the element is resolved using document.querySelector
+// passing a CSS selector
+// the element referenced by the selector is determined using document.querySelector
 
-jump('#target')
+jump('.target')
 ```
 
 ### duration
@@ -111,7 +112,7 @@ jump('.target', {
 })
 ```
 
-Or, pass a function accepting `distance` (in `px`) as an argument, that returns the duration of the `jump()`, in milliseconds.
+Or, pass a function that returns the duration of the `jump()` in milliseconds. This function is passed the `jump()` `distance`, in `px`, as a parameter.
 
 ```es6
 jump('.target', {
@@ -137,24 +138,18 @@ jump('.target', {
 })
 ```
 
-Note that this option is useful for accommodating elements `position: fixed` to the top/bottom of the screen.
+Note that this option is useful for accommodating `position: fixed` elements.
 
 ### callback
 
-Pass a function to be called after the `jump()` has been completed.
+Pass a function that will be called after the `jump()` has been completed.
 
 ```es6
-// in both regular and arrow functions, 'this' === 'window'
+// in both regular and arrow functions, this === window
 
 jump('.target', {
   callback: () => console.log('Jump completed!')
 })
-
-jump('.target', {
-  callback: function() {
-    console.log('Jump completed!')
-  }
-})
 ```
 
 ### easing
@@ -171,7 +166,10 @@ See [easing.js](https://github.com/callmecavs/jump.js/blob/master/src/easing.js)
 
 ### a11y
 
-If enabled, _and scrolling to an element_, add a [`tabindex`](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/tabindex) to, and [`focus`](https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/focus), the element.
+If enabled, _and scrolling to an element_:
+
+* add a [`tabindex`](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/tabindex) to, and
+* [`focus`](https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement/focus) the element
 
 ```es6
 jump('.target', {