Add md files for auto index pages

Part of IA and Redocly migration work. Create simple .md files to
represent the automatic index pages that previously only existed in
the dactyl-config.yml file. (The code used to do this is also part
of the commit but is, hopefully, no longer needed.)

content/infrastructure/configure-rippled/data-retention/index.md

@@ -0,0 +1,6 @@
+---
+html: data-retention.html
+parent: configure-rippled.html
+template: pagetype-category.html.jinja
+---
+# Data Retention

content/infrastructure/configure-rippled/index.md

@@ -0,0 +1,7 @@
+---
+html: configure-rippled.html
+parent: infrastructure.html
+template: pagetype-category.html.jinja
+---
+# Configure rippled
+Customize your rippled server configuration.

content/infrastructure/configure-rippled/server-modes/index.md

@@ -0,0 +1,6 @@
+---
+html: server-modes.html
+parent: configure-rippled.html
+template: pagetype-category.html.jinja
+---
+# Server Modes

content/infrastructure/index.md

@@ -0,0 +1,8 @@
+---
+html: infrastructure.html
+parent: docs.html
+template: pagetype-category.html.jinja
+top_nav_grouping: Article Types
+---
+# Infrastructure
+Install, configure, and manage the software that powers the XRP Ledger.

content/infrastructure/install-rippled/index.md

@@ -0,0 +1,8 @@
+---
+html: install-rippled.html
+parent: infrastructure.html
+top_nav_name: Install & Configure
+template: pagetype-category.html.jinja
+---
+# Install rippled
+Install and update the rippled server.

content/infrastructure/testing-and-auditing/index.md

@@ -0,0 +1,7 @@
+---
+html: use-stand-alone-mode.html
+parent: infrastructure.html
+template: pagetype-category.html.jinja
+---
+# Testing and Auditing
+For new features and experiments, you can use Stand-Alone Mode to test features with a full network.

content/infrastructure/troubleshooting/index.md

@@ -0,0 +1,7 @@
+---
+html: troubleshoot-the-rippled-server.html
+parent: infrastructure.html
+template: pagetype-category.html.jinja
+---
+# Troubleshooting
+Troubleshoot all kinds of problems with the rippled server.