mention that X10 works fine with WSL

I successfully built X10 on WSL after installing make, g++, openjdk-8-jdk and ant. 
I had to manually increase the minimum size for the Windows page file to get around a 'Cannot 
allocate memory' error when forking processes, but apparently this will be fixed in a future build:
see microsoft/WSL#1019

x10-development/building-x10-from-source.html

@@ -13,7 +13,9 @@ <h3><a name="BuildingFromSource-AssumptionsandPrerequisites"></a>Assumptions and
 <p>You will also need <a href="http://ant.apache.org/">Ant</a> 1.7.1 or better, as well as <tt>g++</tt> 4.4 or better (optionally <tt>xlC</tt> 11.1 or better), binutils, <tt>wget</tt>, and GNU <tt>make</tt>.</p>
 <p>Note for Linux users: The X10 build uses the <tt>javah</tt> task, which is not included in the default <tt>ant</tt> package. You would need to install <tt>ant-nodeps</tt> (on RedHat/Gentoo-based systems) or <tt>ant-optional</tt> (on Debian/SuSE-based systems).</p>
 <p>Note for MacOS users: The default Java installation on recent versions of MacOS is not a complete JDK even if it comes with the javac compiler. You must install a proper JDK to build X10 from sources, that is, either a Java Developer Package for Java 6 from Apple or a Java 7 JDK from Oracle. If JAVA_HOME is not set, the build will use the preferred Java installation as returned by /usr/libexec/java_home.</p>
-<p>Note for Windows users: You must build X10 within <a href="http://www.cygwin.com/">the cygwin environment</a>. The minimum Cygwin version required to build X10 is 1.7.1, as Cygwin releases prior to 1.7.1 broke the shared library behavior of g++ 4.3.2.&nbsp; Make sure you have these packages:&nbsp; gcc, g++, wget, make, binutils, diffutils, libtool, git, patch, time.</p>
+<p>Note for Windows users: You can build X10 within <a href="http://www.cygwin.com/">the cygwin environment</a>. The minimum Cygwin version required to build X10 is 1.7.1, as Cygwin releases prior to 1.7.1 broke the shared library behavior of g++ 4.3.2.&nbsp;
+   Make sure you have these packages:&nbsp; gcc, g++, wget, make, binutils, diffutils, libtool, git, patch, time.
+   If you are running a 64-bit build of Windows 10, you can also build X10 using the <a href="https://blogs.msdn.microsoft.com/wsl/2016/04/22/windows-subsystem-for-linux-overview/">Windows Subsystem for Linux</a> Ubuntu image.</p>    
 </div>
 <div class="section_3">
 <h3><a name="BuildingFromSource-InitialCheckoutandBuild"></a>Getting the source</h3>