Add intro paragraph

...based on user feedback from dev environment study

Author: mattwojo

WSL/index.md

@@ -8,10 +8,12 @@ ms.localizationpriority: high
 
 # Windows Subsystem for Linux Documentation
 
+The Windows Subsystem for Linux lets developers run a GNU/Linux environment -- including most command-line tools, utilities, and applications -- directly on Windows, unmodified, without the overhead of a traditional virtual machine or dualboot setup.
+
 ## Learn more here
 
 * [What is the Windows Subsystem for Linux?](about.md)
-* [What's new with WSL2?](wsl2-index.md)
+* [What's new with WSL 2?](wsl2-index.md)
 * [Compare WSL 2 and WSL 1](compare-versions.md)
 * [Read frequently asked questions](faq.md)