feat: add theme settings section to README for advanced customization options

README.md

@@ -16,6 +16,7 @@ This plugin is based on my manual mod (see the [legacy branch](https://github.co
   - [Installation](#installation)
   - [Configuration](#configuration)
   - [Automatic Theme Selection](#automatic-theme-selection)
+  - [Theme Settings](#theme-settings)
   - [Build Process](#build-process)
   - [Troubleshooting](#troubleshooting)
     - [Effects Not Showing](#effects-not-showing)
@@ -115,6 +116,9 @@ If automatic selection is enabled, the following themes are applied based on the
 
 > **Note:** Holiday themes (like `santa` or `fireworks`) override monthly seasonal themes (like `snowflakes`).
 
+## Theme Settings
+Each theme contains additional settings to customize its behavior. Expand the advanced configuration section to configure each theme, adjust parameters like particle count, animation speed etc.
+
 ## Build Process
 
 If you want to build the plugin yourself: