I have implemented a document library in which a person assign a document to review to a responsible person. He assigns it selecting his name from the Responsible column. Then an email goes to that person to review it. If he doesn't review it then the creator of the document again assign the document to a responsible person and son till he review it. I have implemented all these things in workflow.
In addition, I want a history column that stores all the dates when the creator has assigned the document. For example, a creator assigns the document first time on 19 October 2016 and the responsible person does not review it. Then the creator again assigns the document on 23 October 2016. I want to store all the dates such as 19 October 2016 and 23 October 2016 dates as a history in a separated column in the document library.