Add correct newspopup plugin README

Author: manisandro

src/plugins/newspopup/README.md

@@ -1,19 +1,25 @@
-Config Editor Plugin
-====================
-
-This plugin adds editors for the input configs `tenantConfig.json` and `config.json` to the Admin GUI.
-
-Uses Ace v1.4.14 code editor from https://ace.c9.io
+NewsPopup Plugin
+================
 
+This plugin adds an editor for editing the contents of the `NewsPopup` displayed in QWC2.
 
 Usage
 =====
 
-Enable this plugin by setting the following options in the `config` block of the `adminGui` section of the `tenantConfig.json`:
+Make sure the `NewsPopup` plugin is enabled in your QWC2 `config.json`. Then, enable this plugin by setting the following options in the `config` block of the `adminGui` section of the `tenantConfig.json`:
+
+```json
+"plugins": ["newspopup"],
+"news_file": "<path_to_news.html>",
+"viewer_config_file": "<path_to_config.json>"
+```
 
+For example
 ```json
-"plugins": ["config_editor"],
-"input_config_path": "<path to the input configs>"
+"news_file": "/qwc2/assets/news.html",
+"viewer_config_file": "/qwc2/config.json"
 ```
 
-The Admin GUI requires write access to the `input_config_path`.
+The plugin requires write access to the files specified by `news_file` and `viewer_config_file` (i.e. the files need to be mounted read-write into the container).
+
+The plugin will display an editor to modify the contents of `news_file` and update the `NewsPopup` plugin configuration in `viewer_config_file`.