Add documentation for "Hide whitespace changes" button

doc/workflow/merge_requests.md

@@ -14,7 +14,7 @@ Locate the section for your GitLab remote in the `.git/config` file. It looks li
 
 Now add the line `fetch = +refs/merge-requests/*/head:refs/remotes/origin/merge-requests/*` to this section.
 
-It should looks like this: 
+It should look like this:
 
 ```
 [remote "origin"]
@@ -43,7 +43,7 @@ $ git checkout origin/merge-requests/1
 
 ![MR diff](merge_requests/merge_request_diff.png)
 
-It you add `w=1` option to URL, you can see diff without whitespace changes.
+If you click to "Hide whitespace changes" button, you can see diff without whitespace changes.
 
 ![MR diff without whitespace](merge_requests/merge_request_diff_without_whitespace.png)
 

spec/features/merge_requests/toggle_whitespace_changes.rb

@@ -13,7 +13,7 @@ feature 'Toggle Whitespace Changes', js: true, feature: true do
     expect(page).to have_content "Hide whitespace changes"
   end
 
-  describe 'clicking hide whitespace changes button' do
+  describe 'clicking "Hide whitespace changes" button' do
     it 'should hide whitespace changes' do
       find('a', text: "Hide whitespace changes").click
       expect(page).to have_content "Show whitespace changes"