message: added instructions for disabling SIP or signing KEXTs
  Added a documentation section for kext signatures
diff: @@ -24,6 +24,20 @@ Then do the following:
  3) copy MSRKernel.h to a location on your path (auto-install uses /usr/include)
  4) copy MSRAccessorPublic.h as MSRAccessor.h to a location on your path (auto-install uses /usr/include)
  +kext Signatures
  +---------------
  +As of OS X El Capitan, kexts must be signed. So after building the kext, kextload.sh may fail with:
  +
  + /System/Library/Extensions/PcmMsrDriver.kext failed to load - (libkern/kext) not loadable (reason unspecified); check the system/kernel logs for errors or try kextutil(8).
  +
  +In this event, you will need to either disable System Integrity Protection or sign the kext.
  +You can disable SIP by rebooting into Recovery (reboot, command-option-R), opening a shell, csrutil disable and reboot again.
  +Signing a kext is more involved. You can't self-sign and will first need to obtain a Developer ID from Apple:
  +
  + https://developer.apple.com/contact/kext/
  +
  +With this ID, you can then sign your kext with codesign.
  +
  PCM Binary Compilation
  ----------------------
  