doc: Drop no longer needed workaround for WSL

This change effectively reverts 4f890ba.

Author: hebasto

doc/build-windows.md

@@ -66,7 +66,6 @@ is to temporarily disable WSL support for Win32 applications.
 
 Build using:
 
-    PATH=$(echo "$PATH" | sed -e 's/:\/mnt.*//g') # strip out problematic Windows %PATH% imported var
     sudo bash -c "echo 0 > /proc/sys/fs/binfmt_misc/status" # Disable WSL support for Win32 applications.
     cd depends
     make HOST=x86_64-w64-mingw32