cansend: print canfd_frame.flags in help text

[marckleinebudde]

Add the struct canfd_frame::flags to the help text.

--- old 2025-11-07 12:25:48.087802351 +0100
+++ new 2025-11-07 12:25:56.915751150 +0100
@@ -19,7 +19,10 @@
 _{dlc}:
  an optional 9..F data length code value when payload length is 8
 <flags>:
- a single ASCII Hex value (0 .. F) which defines canfd_frame.flags
+ a single ASCII Hex value (0 .. F) which defines canfd_frame.flags:
+ 1 CANFD_BRS
+ 2 CANFD_ESI
+ 4 CANFD_FEF
 
 <vcid>:
  2 hex chars - virtual CAN network identifier (00 .. FF)

[hartkopp]

The flag is named CANFD_FDF and not CANFD_FEF
;-)

[marckleinebudde]

doh! will fix