revsets: mention squash into

This should really be introduced in "The Squash Workflow" to explain how it has the exact same power as the Edit Workflow, but I'm not up for that much writing right now

Author: riking

src/branching-merging-and-conflicts/revsets.md

@@ -28,8 +28,9 @@ example, remember how in the squash workflow, we would move the contents of
 the working directory into the parent change? Well, the `-` operator refers to
 the parent of a given revision, and `@` is the change referring to the current
 working directory, so we might say "we squashed the contents of `@` into `@-`.
-And in fact, `jj squash` is short for `jj squash -r @`. There are many operators,
-including, but not limited to:
+And in fact, `jj squash` is short for `jj squash -r @` or equivalently `jj
+squash --from @ --into @-`. There are many operators, including, but not
+limited to:
 
 * `x & y`: changes that are in both x and y
 * `x | y`: changes that are in either x or y