Re-level non-docs content to top of repo and rename content→docs

docs/tutorials/java/index.md

@@ -0,0 +1,13 @@
+---
+html: java.html
+parent: tutorials.html
+top_nav_grouping: Article Types
+metadata:
+  indexPage: true
+---
+# Java
+
+XRPL tutorials in Java.
+
+
+{% child-pages /%}