Transformed summaries are generally fair use already (or perhaps not even an issue of copyright). You can read plot summaries of novels and movies on Wikipedia, same with technical topics. The ideas are not protected by copyright, the artistic expression is. Certain technical ideas can be protected via patents. But even then, not the description of idea, but putting it into practice. Ideas that you're not supposed to re-summarize in your own words at all are things like trade secrets or classified information.