README: Add warning about writing data to HID products

[Qbicz]

In response to #105

[Qbicz]

@Youw @z3ntu @amosbird can you review?

[z3ntu]

programs instead of programmes? I know it's a bit British vs American English but it's more fitting in this context.

[Qbicz]

applications ;)

[z3ntu]

I would use *s instead of `s, so to make it bold because it looks a bit weird in this preformatted style.

[Qbicz]

done

[Youw]

only against devices which firmware
you control

This statement is a bit too strong - you may not nesessary control the FW, but safely write, e.g. if you have official spec, etc.

I was thinking, maybe add explicit check for dev/ven before hid_write in the example

[Qbicz]

This statement is a bit too strong - you may not nesessary control the FW, but safely write, e.g. if you have official spec, etc.

@Youw done.

I was thinking, maybe add explicit check for dev/ven before hid_write in the example

I think that would be too much, since to write to the device in the sample you have to enumerate devices, check vid/pid and hardcode it to the sample. Or do you mean interactive check like with gets()?

[Youw]

I was thinking something like:

#define SAMPLE_VEN_ID ...
#define SAMPLE_DEV_ID ...
unsigned short ven_id = SAMPLE_VEN_ID;
unsigned short dev_id = SAMPLE_DEV_ID;

int main(/*...*/) {
  if (argc /* ... */ ) {
    // ...
    ven_id = // parse arguments, etc.
    // ...
  }

  handle = hid_open(ven_id, dev_id, NULL);
  // ...

  // a WARNING comment here, what we're know what we're doing, but only with a specific device
  if (ven_id == SAMPLE_VEN_ID && dev_id == SAMPLE_DEV_ID) {
    // ...
    res = hid_write(handle, buf, 65);
    // ...
  }
  // hid_close
  // hid_exit
}

So we can include #14 and a little more, like explicitly encourage to hid_close which is not in an example.

---

Maybe this is a little too large change, but anyway nice to have.

[Qbicz]

@Youw thanks for your comments, I added hid_close() call to the sample as you suggested, so this is now explicitly visible.

[Youw]

and let's merge it after #115