Add an "Edit on GitHub" button to Documentation

## Description:
Add an "Edit on GitHub" button to Documentation.

The button will link the user directly to the asciidoc document at GitHub and open it in editing mode (if possible). An example of such behavior can be found at https://next.adoptopenjdk.net/migration (see link at bottom of the page) or at https://nodejs.org/en/docs/guides/getting-started-guide/. A link to edit a file directly can be based on a simple simple pattern: https://github.com/[TEAM]/[REPO]/edit/master/src/documenation/[DOC-NAME]/index.adoc

## Acceptance criteria:
- Button redirects to https://github.com/[TEAM]/[REPO]/edit/master/src/documenation/[DOC-NAME]/index.adoc
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## Sketches / Mockups:
See in top-right of sketch