chore: Upgrade Docusaurus from v2 to v3 (#52)

* chore: Upgrade Docusaurus from v2 to v3

* chore: Update "Test build" GH workflow

* fix: build

All markdown is processed as MDX

* fix: Broken links

library/modules/custom-html/README.md

@@ -3,7 +3,7 @@ title: Custom HTML
 hide_title: true
 ---
 
-<##head##>
+{/*##head##*/}
 
 # Custom HTML
 
@@ -27,7 +27,7 @@ You can pass dynamic values to your markup by using template strings. `{{ FillCo
 
 This node also allows you to add script tags to your app. For security reasons all script tags are deactivated, but if you need to run a script (required for some embeds) you can turn off that fail safe. <strong>Please note that passing user input to your template string variables can be a security risk for you and your users, leaving you vulnerable to [XSS Attacks](https://en.wikipedia.org/wiki/Cross-site_scripting).</strong>
 
-<##head##>
+{/*##head##*/}
 
 ## Inputs