Added a note for an issue

Build-instructions-(Ubuntu).md

@@ -68,11 +68,21 @@ Now it's time to build Proton itself:
     $ ../proton/configure.sh --steam-runtime64=docker:steam-proton-dev --steam-runtime32=docker:steam-proton-dev32 --steam-runtime=$HOME/steam-runtime/runtime/ --build-name="proton-mybuild"
     $ make
 
+### Possible Make Errors
+
 If you encounter the error `mutex in namespace std does not name a type`, you will need to do the following (as noted on [Stack Overflow](https://stackoverflow.com/questions/14191566/c-mutex-in-namespace-std-does-not-name-a-type)):
 
     $ cd $(dirname $(which i686-w64-mingw32-g++))
     $ sudo ln -s ./i686-w64-mingw32-g++-posix i686-w64-mingw32-g++
 
+If you encounter the error `fatal error: dxgi.h: No such file or directory`, I have not found a good fix, however, you can add this line to the makefile to compile without dxvk:
+
+    NO_DXVK := 1
+
+*If anyone finds a better fix for the above issue, please update this page.*
+
+## Packaging and Installation
+
 To package Proton after successful build:
 
     $ make dist