Improve readme, refactor spec for position

Author: route

README.md

@@ -234,12 +234,23 @@ browser.go_to("https://github.com/")
 browser.stop
 ```
 
-#### position
+#### position = \*\*options
 
-Set the position for the browser window bounds
+Set the position for the browser window
+
+* options `Hash`
+  * :left `Integer`
+  * :top `Integer`
 
 ```ruby
 browser.position = { left: 10, top: 20 }
+```
+
+#### position : `Array<Integer>`
+
+Get the position for the browser window
+
+```ruby
 browser.position # => [10, 20]
 ```
 

spec/browser_spec.rb

@@ -126,10 +126,11 @@ module Ferrum
     end
 
     it "allows the window to be positioned" do
-      expect(browser.position).to eq([0, 0])
-      expect { browser.position = { left: 10, top: 20 } }.
-        to change { browser.position }
-      expect(browser.position).to eq([10, 20])
+      expect {
+        browser.position = { left: 10, top: 20 }
+      }.to change {
+        browser.position
+      }.from([0, 0]).to([10, 20])
     end
 
     it "allows the page to be scrolled" do