* Added the working-with-nodes-api-service tutorial.
* Added the 'Alfresco Example Content Application' paragraph to the 'Preparing the development environment' tutorial.
* Added the tutorial 'Creating your JavaScript application using alfresco-js-api'.
* Added the image of the tutorial.
* Typo in 'creating-javascript-app-using-alfresco-js-api.md'
Typo in 'Prerequisites'.
* Typos in 'creating-javascript-app-using-alfresco-js-api.md'
Two small typos.
* Wrong sentence in 'creating-javascript-app-using-alfresco-js-api.md'
...into Angular applications, but it is "framework agnostic".
* Typo on 'creating-javascript-app-using-alfresco-js-api.md'.
...and Angular...
