[documentation] improve README.md with regards to mingw64

Signed-off-by: Steffen Kuhn <nielson2@yandex.com>

README.md

@@ -33,7 +33,7 @@ export WINEPREFIX=/path/to/.wine-prefix
 ### Requirements:
 - [wine 3.10](https://www.winehq.org/) or newer
 - [Meson](http://mesonbuild.com/) build system (at least version 0.46)
-- [MinGW64](http://mingw-w64.org/) 6.0 compiler and headers
+- [MinGW64](http://mingw-w64.org/) compiler and headers (at least version 6.0)
 - [glslang](https://github.com/KhronosGroup/glslang) compiler
 
 ### Building DLLs
@@ -111,11 +111,16 @@ The following environment variables can be used for **debugging** purposes.
 
 ## Troubleshooting
 DXVK requires threading support from your mingw-w64 build environment. If you
-are missing this, you may see "error: 'mutex' is not a member of 'std'". On
-Debian and Ubuntu, this can usually be resolved by using the posix alternate, which
+are missing this, you may see "error: 'mutex' is not a member of 'std'". 
+
+On Debian and Ubuntu, this can be resolved by using the posix alternate, which
 supports threading. For example, choose the posix alternate from these
 commands (use i686 for 32-bit):
 ```
 update-alternatives --config x86_64-w64-mingw32-gcc
 update-alternatives --config x86_64-w64-mingw32-g++
 ```
+For non debian based distros, make sure that your mingw-w64-gcc cross compiler 
+does have `--enable-threads=posix` enabled during configure. If your distro does
+ship it's mingw-w64-gcc binary with `--enable-threads=win32` you might have to
+recompile locally or open a bug at your distro's bugtracker to ask for it.