[DOC] Cleanup packet descriptions that have a variable data length

There are packets that have a variable data length typically showing up as an 8-bit array at the end of the packet's data part (e.g. abData[]). 

Those arrays shall not show the array length as defined in the corresponding header file, but shall only have empty brackets "[]".

For request packets the range for the number of bytes (typically named "n") shall be stated in the description column rather than in the value/range column.