track changes/version control for legal/SEC compliance

I am searching for a solution, please help.

I need something to assist regarding the handling of updates of content on the site. We need a system to document each site update for our records. In addition, we need to have somewhere on the web page “Version 1.x with the date” each time we do an update. This would include simple things such as the addition of a new commentary or a phone number change.

This can certainly be accomplished manually, but can we do it automatically? Are there plug-ins or items already in the wordpress to accomplish this goal?