Type: the thread-break comments describe the behaviour in our own words

Review follow-up (CodeRabbit, clean-room): two doc comments quoted the
cited help page. Comments only.

crates/engine/src/cmd/threads.rs

@@ -658,8 +658,8 @@ fn remove(s: &mut Session, _: &Value) -> Result<Value> {
 }
 
 /// `text.thread.break`: a double-click on a threaded port. The thread is split there; the whole
-/// story goes into the first part, "the text flows into the first object", and the frames of the
-/// second part are emptied, staying threaded with each other when two or more remain.
+/// story moves into the frames before the split, and the frames after it are emptied, staying
+/// threaded with each other when two or more remain.
 fn break_thread(s: &mut Session, p: &Value) -> Result<Value> {
     const C: &str = "text.thread.break";
     let id = checked_id(s, p.get("id").unwrap_or(&Value::Null), C)?;

crates/tools/src/select.rs

@@ -24,8 +24,8 @@
 //! frame (`text.thread.add`), which comes after the clicked one in its thread. A click on the in
 //! port does the same with the new frame put before it: the story then starts there and flows on
 //! into the clicked one. Escape drops the loaded text. A double-click on a port where the frame is
-//! threaded breaks the thread there (`text.thread.break`): "To break the thread between two
-//! objects, double-click the port on either end of the thread"
+//! threaded splits the thread at that port (`text.thread.break`), as the archived help section on
+//! threading describes
 //! (<https://web.archive.org/web/20220127090642/https://helpx.adobe.com/illustrator/using/creating-text.html>).
 //! With Smart Guides and Invoke Distance Guides on, Alt/Option held over another object shows how
 //! far the selection is from it, and over an empty part of an artboard how far it is from the