How to document Lessons Learned Effectively?

I am working on developing my company's knowledge base. I am currently working on Lessons Learned for each project. 

I am curious to learn how the community has used Wrike to document lessons learned. I've seen a lot of word and excel templates but have not been able to find one in Wrike. 

How do you document lessons learned and what system do you use? How do you collect lessons from your team?

Thank you,

Lea (Wrike Newbie)