Removing "Windows is not officially tested"

According to the dev, this is no longer the case.  We did test the integration with Notary for Windows images.  Let me know if you need more information around this.
 
"Windows is not officially tested, but if you are a developer and Windows user,
we would appreciate any insight you can provide regarding issues."

notary/getting_started.md

@@ -27,8 +27,6 @@ freshness of your content.
 You can download precompiled notary binary for 64 bit Linux or macOS from the
 Notary repository's
 [Releases page on Github](https://github.com/docker/notary/releases).
-Windows is not officially tested, but if you are a developer and Windows user,
-we would appreciate any insight you can provide regarding issues.
 
 ## Understand Notary naming