add editor hint to README.md

README.md

@@ -30,26 +30,29 @@ To find out more about the installation, you can also [read on here](#installing
 
 ## Usage
 
-1. In a Moodle course you can add a board to different types of content, i.e.:
-   - `Add an activity or resource -> Page`
-   - `Add an activity or resource -> Link`
-   - `Add an activity or resource -> Quiz`
-   - ...
-2. Write content. At the position the construction should appear, create a construction by:
-	* switching to the code input, i.e. to "HTML source editor"
-	* inserting a `<jsxgraph>` tag with all required parameters
-	* Each <code><div\></code> that contains a JSXGraph board needs a unique ID on the page. This ID is generated automatically. Reference it within the JavaScript using the constant <code>BOARDID</code>.
-
-   Example: 
-
-   ```html
-   <jsxgraph width="500" aspect-ratio="1/1">
-       var brd = JXG.JSXGraph.initBoard(BOARDID, {boundingbox:[-5,5,5,-5], axis:true});
-       var p = brd.create('point', [1,2]);
-   </jsxgraph>
-   ```
+In a Moodle course you can add a board to different types of content, i.e.: `Page`, `Link`, `Quiz`, ...
+
+At the position the construction should appear, create a construction by:
+* switching to the code input, i.e. to "HTML source editor" **(*)**
+* inserting a `<jsxgraph>` tag with all required parameters
+* Each <code><div\></code> that contains a JSXGraph board needs a unique ID on the page. This ID is generated automatically. Reference it within the JavaScript using the constant <code>BOARDID</code>.
+
+**(*) Important notice:**   
+Please note that some Moodle editors remove the `<jsxgraph>` tag when saving.
+As a result, the construction may not be displayed correctly or at all.
+You should therefore always use the "Plain text editor".
+Some also report that the "Atto HTML editor" works, too.
+
+Example: 
+
+```html
+<jsxgraph width="500" aspect-ratio="1/1">
+   var brd = JXG.JSXGraph.initBoard(BOARDID, {boundingbox:[-5,5,5,-5], axis:true});
+   var p = brd.create('point', [1,2]);
+</jsxgraph>
+```
 
-Get many examples for constructions at [jsxgraph.org/share](https://jsxgraph.org/share). There you can export them to the JSXGraph Moodle filter format.
+Get many examples for constructions at [https://jsxgraph.org/share](https://jsxgraph.org/share). There you can export them to the JSXGraph Moodle filter format.
 
 ***For tag attributes and global settings have a look at [Attributes and settings](#attributes-and-settings) in this documentation.***