Correct downsampling and better layout

src/config.hpp

@@ -27,7 +27,8 @@ struct Config {
   double trigger_holdoff_s = 0.010;
   int recv_buffer_bytes = 8 * 1024 * 1024;
 
-  /// Number of stacked plots (rows) to start with, 1..4.
+  /// Number of stacked plots (rows) to start with, 1..`RowSet::kMaxRows`. Only the
+  /// starting point: rows are added and removed from the layout editor.
   int plots = 1;
 };