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/references/http-websocket-apis/index.md

@@ -1,8 +1,12 @@
 ---
 html: http-websocket-apis.html
 parent: references.html
-template: pagetype-category.html.jinja
+metadata:
+  indexPage: true
 ---
 # HTTP / WebSocket APIs
 
-Communicate directly with rippled, the core peer-to-peer server that manages the XRP Ledger.
+Communicate directly with rippled, the core peer-to-peer server that manages the XRP Ledger.
+
+
+{% child-pages /%}