udev.rules documentation improvement (libusb#326)

As recently discovered (thanks @tresf), the `TAG+="uaccess"` has to be used
before `73-seat-late.rules` and not before `70-uaccess.rules`.

Technically it doesn't harm to have a more restrictive recommenration,
but it was not technically correct.

Refference on `uaccess` TAG consumption:
[1](https://github.com/systemd/systemd/blob/3a1220eedfb65355c387c29584380742a21917aa/src/login/73-seat-late.rules.in), [2](https://www.apt-browse.org/browse/debian/wheezy/main/amd64/systemd/44-11+deb7u4/file/lib/udev/rules.d/73-seat-late.rules).

udev/69-hid.rules

@@ -16,17 +16,20 @@ SUBSYSTEM=="usb", ATTRS{idVendor}=="04d8", ATTRS{idProduct}=="003f", TAG+="uacce
 KERNEL=="hidraw*", ATTRS{idVendor}=="04d8", ATTRS{idProduct}=="003f", TAG+="uaccess"
 
 # Once done, optionally rename this file for your application, and drop it into
-# /etc/udev/rules.d. Note that these rules must have priorty before 70-uaccess.rules
-# for example, name the file /etc/udev/rules.d/69-my-application-hid.rules.
+# /etc/udev/rules.d/.
+# NOTE: these rules must have priorty before 73-seat-late.rules.
+# (Small discussion/explanation in systemd repo:
+#  https://github.com/systemd/systemd/issues/4288#issuecomment-348166161)
+# for example, name the file /etc/udev/rules.d/70-my-application-hid.rules.
 # Then, replug your device or run:
 # sudo udevadm control --reload-rules && sudo udevadm trigger
 
 # Note that the hexadecimal values for VID and PID are case sensitive and
 # must be lower case.
 
 # TAG+="uaccess" only gives permission to physically present users, which
-# is appropriate in most scenarios. If you require remote access to the
-# device, add
+# is appropriate in most scenarios. If you require access to the device
+# from a remote session (e.g. over SSH), add
 # GROUP="plugdev", MODE="660"
 # to the end of the udev rule lines, add your user to the plugdev group with:
 # usermod -aG plugdev USERNAME