Update nextcloud docs to better address config manipulation

fighter/config/nextcloud/README.md

@@ -1,4 +1,32 @@
-# Config Snippets for `config.php`
+# Config Snippets for `default.conf` Nginx config
+The Nginx server inside the container manages many aspects of connectivity for the Nextcloud server. 
+The `default.conf` here is for reference only.
+The effective `default.conf` file is located at: `/config/nginx/site-confs/default.conf`.
+
+
+## Increase Upload Limits
+In the `server {` block:
+```conf
+client_max_body_size 50G;
+client_body_timeout 600s;
+```
+
+# Config Snippets for `php-local.ini` PHP config override
+It seems the preferred mode for modifying Nextcloud's PHP config is via `php.ini`, located at `/config/php/php-local.ini`.
+
+## Increase Upload Limits
+```ini
+upload_max_filesize = 8192M
+post_max_size = 8192M
+max_execution_time = 600
+```
+
+## Increase PHP Memory Limit
+```ini
+memory_limit = 4G
+```
+
+# Config Snippets for `config.php` PHP config
 The Nextcloud server is configured via `config.php` at `$DOCKER_DATA/config/www/nextcloud/config/`. We make changes to this file manually, and then restart or recreate the container to apply the changes.
 
 All configuration parameters are contained in the `<?php $CONFIG=array (` block.
@@ -37,3 +65,29 @@ All configuration parameters are contained in the `<?php $CONFIG=array (` block.
     'password' => '', // Optional, if not defined no password will be used.
   ),
 ```
+
+## HEIC Image Previews
+```php
+  'enable_previews' => true,
+  'enabledPreviewProviders' =>
+  array (
+    'OC\Preview\PNG',
+    'OC\Preview\JPEG',
+    'OC\Preview\GIF',
+    'OC\Preview\BMP',
+    'OC\Preview\XBitmap',
+    'OC\Preview\MP3',
+    'OC\Preview\TXT',
+    'OC\Preview\MarkDown',
+    'OC\Preview\OpenDocument',
+    'OC\Preview\Krita',
+    'OC\Preview\HEIC',
+  ),
+```
+
+## Increase Upload Limits
+```php
+  upload_max_filesize = 2048M
+  post_max_size = 2048M
+  max_execution_time = 200
+```