Update README.md.

I updated and added details about gotchas I ran into when attempting this fix on my Ubuntu machine.
This should address the problems encountered in patjak#55, patjak#59, and patjak#65.

README.md

@@ -16,11 +16,28 @@ At this point you can load the module
 
 Then restart X (usually log in / log out will do the trick). The module should automatically load on next boot on any MacBook Air 6,x.
 
+### If brightness control still doesn't work:
+
+You may need to follow the directions suggested in [#65](https://github.com/patjak/mba6x_bl/issues/65) and do the following:
+1. Create `usr/share/X11/xorg.conf.d/98-mba6bl.conf`.
+2. In that file, enter the following content (from  [here](https://github.com/patjak/mba6x_bl/blob/master/98-mba_bl.conf)):
+```
+Section "Device"
+  Identifier "Intel Graphics"
+  Driver "Intel"
+  Option "Backlight"  "mba6x_backlight"
+EndSection
+```
+3. Remove `/usr/share/X11/xorg.conf.d/20-intel.conf` or move it to a backup directory.
+4. Log in/log out or `$ reboot`.
+
+
 ## Debian dkms package
 
 You can either follow the long route <https://wiki.kubuntu.org/Kernel/Dev/DKMSPackaging>, or
-download a pre-made .deb file from <http://miek.nl/downloads/2015/mba6xbl-dkms_1.0.0_all.deb>,
-which can be installed with `dpkg -i`.
+download a pre-made .deb.zip file of v1.1.0 from
+<https://github.com/patjak/mba6x_bl/files/505288/mba6xbl-dkms_1.1.0_all.deb.zip>,
+which can be installed with `dpkg -i`. (Installing v1.0.0 can result in build errors; see [#55](https://github.com/patjak/mba6x_bl/issues/55).)
 
 ## Ubuntu specific instructions
 <https://help.ubuntu.com/community/MacBookAir6-2/Trusty#Backlight>