[Cin] Add to the manual

[Andrea paz]

I'm sorry Phyllis but I explained the Compositor thing wrong. I meant
that a fourth item, that is, using the tools in the Compositing window
during editing, could affect the result of the render file. Instead it
does not: all operations in the Compositor window do not affect the
render, only the three items that are listed have influence.
I had put a sentence inside the "timeline" item because it is in the
Compositor that we see the timeline and we might be led to think that
these tools are also influential. But the Compositor only serves as a
display for the timeline.
It may be best to remove the Compositor part.
Sorry for the confusion I created.