Updated the index.md with some grammatical changes (sitespeedio#3083)

docs/documentation/sitespeed.io/introduction/index.md

@@ -43,15 +43,15 @@ First a few key concepts:
 
 When you as user choose to test a URL, this is what happens on a high level:
 
- 1. sitespeed.io starts and initialise all configured plugins.
+ 1. sitespeed.io starts and initialises all configured plugins.
  2. The URL is passed around the plugins through the queue.
  1. Browsertime gets the URL and opens the browser.
  2. It starts to record a video of the browser screen.
- 3. The browser access the URL.
+ 3. The browser accesses the URL.
  4. When the page is finished, Browsertime takes a screenshot of the page.
- 5. Then run some JavaScript to analyse the page (using Coach and Browsertime scripts).
- 6. Stop the video and close the browser.
- 7. Analyse the video to get Visual Metrics like First Visual Change and Speed Index.
+ 5. It then runs some JavaScript to analyse the page (using Coach and Browsertime scripts).
+ 6. It stops the video and closes the browser.
+ 7. Analyses the video to get Visual Metrics like First Visual Change and Speed Index.
  8. Browsertime passes all metrics and data on the queue so other plugins can use it.
  3. The HTML/Graphite/InfluxDB plugin collects the metrics in queue.
  4. When all URLs are tested, sitespeed sends a message telling plugins to summarise the metrics and then render it.