Add warning not to edit boards.txt (#383)

boards.txt

+# WARNING - DO NOT EDIT THIS FILE, IT IS MACHINE GENERATED
+#           To change something here, edit tools/makeboards.py and
+#           run 'python3 makeboards.py > ../boards.txt' to regenerate
+
 menu.BoardModel=Model
 menu.flash=Flash Size
 menu.freq=CPU Speed

tools/makeboards.py

@@ -98,6 +98,12 @@ def BuildHeader(name, vendor_name, product_name, vidtouse, pidtouse, vid, pid, p
     print('%s.build.usb_manufacturer="%s"' % (name, vendor_name))
     print('%s.build.usb_product="%s"' % (name, product_name))
 
+def WriteWarning():
+    print("# WARNING - DO NOT EDIT THIS FILE, IT IS MACHINE GENERATED")
+    print("#           To change something here, edit tools/makeboards.py and")
+    print("#           run 'python3 makeboards.py > ../boards.txt' to regenerate")
+    print()
+
 def BuildGlobalMenuList():
     print("menu.BoardModel=Model")
     print("menu.flash=Flash Size")
@@ -147,7 +153,7 @@ def MakeBoard(name, vendor_name, product_name, vid, pid, pwr, boarddefine, flash
         if name == "generic":
             BuildBoot(n)
 
-
+WriteWarning()
 BuildGlobalMenuList()
 MakeBoard("rpipico", "Raspberry Pi", "Pico", "0x2e8a", "0x000a", 250, "RASPBERRY_PI_PICO", 2, "boot2_w25q080_2_padded_checksum")
 MakeBoard("adafruit_feather", "Adafruit", "Feather RP2040", "0x239a", "0x80f1", 250, "ADAFRUIT_FEATHER_RP2040", 8, "boot2_w25x10cl_4_padded_checksum")