DLL-README update for libopenmpt

libs/DLL-README.txt

@@ -7,6 +7,7 @@ Here are the required DLLs, per build. For each architecture, copy all the binar
 * libs\dll-binaries\[i686/x86_64]
 * libs\SDL2\[i686/x86_64]...\bin
 * libs\SDL2_mixer\[i686/x86_64]...\bin
+* libs\libopenmpt\[x86/x86_64]...\bin\mingw
 
 and don't forget to build r_opengl.dll for srb2dd.
 
@@ -17,6 +18,7 @@ and don't forget to build r_opengl.dll for srb2dd.
 * libs\dll-binaries\i686\mgwhelp.dll (depend for exchndl.dll)
 * libs\SDL2\i686-w64-mingw32\bin\SDL2.dll
 * libs\SDL2_mixer\i686-w64-mingw32\bin\*.dll (get everything)
+* libs\libopenmpt\x86\bin\mingw\libopenmpt.dll
 
 ## srb2win, 64-bit
 
@@ -25,6 +27,7 @@ and don't forget to build r_opengl.dll for srb2dd.
 * libs\dll-binaries\x86_64\mgwhelp.dll (depend for exchndl.dll)
 * libs\SDL2\x86_64-w64-mingw32\bin\SDL2.dll
 * libs\SDL2_mixer\x86_64-w64-mingw32\bin\*.dll (get everything)
+* libs\libopenmpt\x86_64\bin\mingw\libopenmpt.dll
 
 ## srb2dd, 32-bit