Migrate content syntax via script

The changes in this commit were auto-generated by running

tool/migrate.sh

Following this commit, the Dactyl build no longer works but the Redocly
build (mostly) should.

content/tutorials/http-websocket-apis/index.md

@@ -2,8 +2,12 @@
 html: http-websocket-apis-tutorials.html
 parent: tutorials.html
 top_nav_grouping: Article Types
-template: pagetype-category.html.jinja
+metadata:
+  indexPage: true
 ---
 # HTTP / Websocket APIs
 
-XRPL tutorials for HTTP / Websocket APIs.
+XRPL tutorials for HTTP / Websocket APIs.
+
+
+{% child-pages /%}