docs: the readouts strip follows the collapsed state

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/USER-GUIDE.md

@@ -21,8 +21,8 @@ The window is a plot with three things around it:
   never resizes the plot;
 - the **dock** on the right, which the dock button in the header bar (`s`) shows and hides: read-only
   **Readouts** of the cursors and of the measurements, each with an **Edit** button that opens its
-  page, and an **Events** block. With the dock hidden, the readouts show in a one-line strip under the
-  plot instead (the cursors' deltas and each measurement's value; **Cursors** and **Measures** open the pages).
+  page, and an **Events** block. With the dock hidden, or in a narrow window where the dock slides over the plot, the readouts show in a
+  one-line strip under the plot instead (the cursors' deltas and each measurement's value; **Cursors** and **Measures** open the pages).
 
 ## 1. Connecting