docs: rewrite README with structured overview and quick start guide

Replaces the minimal project description with a comprehensive README
including a component overview table, quick start instructions, common
Ansible operations, and links to detailed documentation. Aligns with
Red Panda Approval™ standards.

ansible/nextcloud/config.php.j2

@@ -0,0 +1,40 @@
+<?php
+$CONFIG = array (
+  'instanceid' => '{{ nextcloud_instance_id | default("") }}',
+  'passwordsalt' => '{{ nextcloud_password_salt | default("") }}',
+  'secret' => '{{ nextcloud_secret | default("") }}',
+  'trusted_domains' => 
+  array (
+    0 => 'rosalind.incus',
+    1 => '{{ nextcloud_domain }}',
+  ),
+  'datadirectory' => '{{ nextcloud_data_dir }}',
+  'dbtype' => 'pgsql',
+  'version' => '',
+  'overwrite.cli.url' => 'https://{{ nextcloud_domain }}',
+  'dbname' => '{{ nextcloud_db_name }}',
+  'dbhost' => '{{ nextcloud_db_host }}:{{ nextcloud_db_port }}',
+  'dbport' => '',
+  'dbtableprefix' => 'oc_',
+  'dbuser' => '{{ nextcloud_db_user }}',
+  'dbpassword' => '{{ nextcloud_db_password }}',
+  'installed' => true,
+  'memcache.local' => '\\OC\\Memcache\\Memcached',
+  'memcache.distributed' => '\\OC\\Memcache\\Memcached',
+  'memcached_servers' => 
+  array (
+    0 => 
+    array (
+      0 => 'localhost',
+      1 => 11211,
+    ),
+  ),
+  'memcached_options' => 
+  array (
+    'prefix' => 'nc_',
+  ),
+  'maintenance' => false,
+  'theme' => '',
+  'loglevel' => 2,
+  'default_phone_region' => 'US',
+);