Re: [PATCH v3 09/13] trailer --parse docs: add explanation for its usefulness

"Linus Arver via GitGitGadget" [off-list ref] writes:

 --parse::
 	A convenience alias for `--only-trailers --only-input
-	--unfold`.
+	--unfold`. This makes it easier to only see the trailers coming from the
+	input without influencing them with any command line options or
+	configuration variables, while also making the output machine-friendly with
+	--unfold.

Nicely explained.  Without a concise explanation like this, it is
hard to see what the value of the "convenience" alias actually is.