Fix CSS Module Template link (#17)

* Fix CSS Module Template link

* Apply suggestions from review

Co-authored-by: sideshowbarker <sideshowbarker@gmail.com>

* Remove filename from the URL

* Update spec/index.md

Co-authored-by: sideshowbarker <sideshowbarker@gmail.com>

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Co-authored-by: sideshowbarker <sideshowbarker@gmail.com>
Co-authored-by: Tab Atkins Jr. <jackalmage@gmail.com>

Author: 3 people

spec/index.md

@@ -17,7 +17,7 @@ The [Status page](/planning/status/) tracks outstanding resolutions. Editors, pl
 
 - [GitHub Workflow](https://w3c.github.io/workflow.html) for editors and other contributors
 - [bikeshed](/tools/bikeshed/) --- generating `Overview.html` from `Overview.bs` (auto-generating section numbers, indices, cross-links, and other mundane things).  (Or here's a guide for the [older processor](/tools/spec-processor/).)
-- [CSS Module Template](http://dev.w3.org/csswg/css-module-bikeshed/Overview.bs) --- for starting new specs (and formatting old ones)
+- [CSS Module Template](https://github.com/w3c/csswg-drafts/blob/main/css-module/Overview.bs) — for starting new specs (and formatting old ones)
 - [format-update](/spec/format-update/) --- for updating existing specs to our latest "specs should include"
 - [check](/spec/check/) -- checking your spec is good to go
 - [publish](/spec/publish/) --- getting your spec on www.w3.org