Documentation: Tracked changes in Google Docs?

Yes. It's called suggestions. Share with Edit permissions. Uncheck the email notifications. Much like MS  Office, comments also exist in Google Docs as well as a Compare option in tools and a revision history (with human readable names that can be set by the user):
https://www.pcmag.com/article/330137/tip-how-to-use-track-changes-in-google-docs

Missing TBC: The Combine (with generated inline tracked changes) option, much useful to know what words changed between 2 revisions when someone forgot (or "forgot") to start tracking changes. If you have PDF versions attempt a conversion of PDF to docx and then combine (Office does it).

Documentation IS part of the configuration of a software so, do learn to use productivity tools. This is why it's called productivity tools.

Collaboration: Promoting online peer reviews

Peer review is essential to improve the quality of your outputs. What about doing it with the community support (not only your team members)? Using Google docs it is possible (out of the box).

Example on how to set it up:
https://cloudsecurityalliance.org/document/ccm-mapping-methodology/

Quoting:
"Participate in the CSA Peer Review

Please fill out the form below to gain access to CCM Mapping Methodology. Use the Comments or Suggesting features on the document to leave your feedback.

To use the Suggestion feature:

Write your comments in-line with the body of the content.Suggestions are associated to your Google Account.

To use the Comment feature:

Highlight the phrase you would like to comment on.Right click and select “Comment“ (or Ctrl+Alt+M).

All suggestions and comments will be reviewed by the editing committee. 
For more information about the collaboration features, please refer to Google’s Support Document.

Fill out the form below to participate."