v1.0.0 - update changelog

Author: gadenbuie

CHANGELOG.md

@@ -1,7 +1,10 @@
 # Change Log
 
-## [UNRELEASED]
+## 1.0.0
 
+The Shiny extension for VS Code now has a new extension ID: `Posit.shiny`! New Shiny users should install the Shiny extension from [the VS Code marketplace](https://marketplace.visualstudio.com/items?itemName=Posit.shiny) or [https://open-vsx.org/extension/posit/shiny](https://open-vsx.org/extension/posit/shiny).
+
+If you previously used the old extension with ID `Posit.shiny-python`, upgrading to the latest version will automatically install the new extension and uninstall the outdated version.
 
 
 ## 0.2.0