Added safety critical comments

heating-boards/heating_driver/heating_driver/heating_driver.kicad_sch

@@ -580,11 +580,20 @@
     (uuid f76a4763-21d4-4bfb-b0c5-9699704102ca)
   )
 
+  (text "Note: This is a lowside driver. \nIf the driven traces find ground anywhere along the way, \nthis circuit will short out."
+    (at 59.69 144.78 0)
+    (effects (font (size 2.5 2.5) (thickness 0.5) bold) (justify left bottom))
+    (uuid 9fdca5c2-1fbd-4774-a9c3-8795a40c206d)
+  )
   (text "Capacitor, diode inductor and mosfet drain \nare to be placed as close to each other as \nphysically possible"
     (at 110.49 82.55 0)
     (effects (font (size 1.27 1.27)) (justify left bottom))
     (uuid a76a574b-1cac-43eb-81e6-0e2e278cea39)
   )
+  (text "PWM freq >= 20 kHz" (at 60.96 104.14 0)
+    (effects (font (size 1.27 1.27)) (justify left bottom))
+    (uuid cc75e5ae-3348-4e7a-bd16-4df685ee47bd)
+  )
 
   (label "ARD_PWM_OUT" (at 53.34 95.25 0)
     (effects (font (size 1.27 1.27)) (justify left bottom))