nv-raw2insights-us: restore the pipeline.yaml header comment

nv-raw2insights-us/pipeline.yaml

@@ -1,3 +1,16 @@
+# Reconstruction pipeline recipe for the NV-Raw2Insights-US example.
+#
+# This file is written by reconstruct.py (pipeline.to_yaml) as a shareable
+# artifact; the pipeline is defined in code, then saved here and loaded back
+# in, so this file is provably what reconstruct.py actually runs. It records
+# the DAS -> envelope -> normalize -> log-compress operation chain; the
+# acquisition/grid parameters are derived from the data file at run time, not
+# stored here.
+#
+# This is the plain DAS recipe, without sound-speed (aberration) correction.
+# reconstruct.py's SoS-corrected panel runs this same pipeline a second time,
+# passing sos_map/sos_grid_x/sos_grid_z to the "beamform" op at call time.
+
 pipeline:
     operations:
     -   name: beamform