readmde: close #148 - link extension page (#149)

Author: balupton

README.md

@@ -4,7 +4,7 @@
 [![vsm-downloads](https://img.shields.io/visual-studio-marketplace/d/TheNuProjectContributors.vscode-nushell-lang?style=flat-square&label=downloads&logo=visual-studio-code)](https://marketplace.visualstudio.com/items?itemName=TheNuProjectContributors.vscode-nushell-lang)
 [![vsm-installs](https://img.shields.io/visual-studio-marketplace/i/TheNuProjectContributors.vscode-nushell-lang?style=flat-square&label=installs&logo=visual-studio-code)](https://marketplace.visualstudio.com/items?itemName=TheNuProjectContributors.vscode-nushell-lang)
 
-This [extension for VSCode](https://code.visualstudio.com/docs/introvideos/extend) provides editing, syntax highlighting, and IDE support for [Nushell](http://nushell.sh), a data-driven document language.
+This [extension for VSCode](https://marketplace.visualstudio.com/items?itemName=TheNuProjectContributors.vscode-nushell-lang) provides editing, syntax highlighting, and IDE support for [Nushell](http://nushell.sh), a data-driven document language.
 
 ## Features