docs(website): support GH page links to canonical src (#2421)

Co-authored-by: Daniel Dyla <dyladan@users.noreply.github.com>

website_docs/_index.md

@@ -1,9 +1,14 @@
 ---
-title: "Javascript"
+title: Javascript
 weight: 20
-description: >
+description: >-
   <img width="35" src="https://raw.github.com/open-telemetry/opentelemetry.io/main/iconography/32x32/JS_SDK.svg"></img>
   A language-specific implementation of OpenTelemetry in JavaScript (for Node.JS & the browser).
+cascade:
+  github_repo: &repo https://github.com/open-telemetry/opentelemetry-js
+  github_subdir: website_docs
+  path_base_for_github_subdir: content/en/docs/js/
+  github_project_repo: *repo
 ---
 
 This page contains an introduction to OpenTelemetry in JavaScript. This guide