Update features.md with current PowerShell version

Update features.md with current PowerShell version (Cloud Shell now runs PowerShell 7.0.0-rc.2)

Author: thomasmaurer

articles/cloud-shell/features.md

@@ -84,7 +84,7 @@ Cloud Shell includes pre-configured authentication for open-source tools such as
 |Go         |1.9        |
 |Java       |1.8        |
 |Node.js    |8.16.0      |
-|PowerShell |[6.2.3](https://github.com/PowerShell/powershell/releases)       |
+|PowerShell |[7.0.0-rc.2](https://github.com/PowerShell/powershell/releases)       |
 |Python     |2.7 and 3.5 (default)|
 
 ## Next steps