Google text Docs, Slides and Drawings do not automatically notify collaborators when an edit has been made. One way you can know if edits to collaborative documents has been made is to go to “Recent” on the left hand side in Google Drive. This will show you documents that have been recently edited. Use the info pane in Drive to view the recent activity on the document.
A good habit to get into is to utilize the “Email collaborators” capability in Docs each time you perform edits to a document. When more than one person is working on a document send a notification to let them know that edits have been made. Quickly collaborators can provide feedback or contribute to the document. This helps a project to be completed faster.
Email Collaborators
Under the “File” menu, choose “Email collaborators…”
Email Notification
Emailing collaborators allows you to write a note to people who are shared on the document. This feature saves you from remembering who you are collaborating with, what their email is and having to switch over to your email. 
Link to Document
The best part of email collaborators is that a link to the Google Doc is automatically included in the email notification. This alerts the collaborator that they can take a look at the edits and allows them to quickly and easily access the document.
