docs: markdown editor example with strange behavior

[tbreuss]

The editor at https://raw.githack.com/MithrilJS/mithril.js/master/examples/editor/index.html is displaying every typed character together with "Type on the left panel and see the result on the right panel". I assume that this is not the expected behavior.

Mithril.js version:

• v2.2

Browser and OS:

• Chrome Version 113.0.5672.92
• Orion Version 0.99.124.1-beta (WebKit 616.1.10)
• Safari Version 16.4.1 (17615.1.26.101.10, 17615)
• Firefox 113.0.1 (64-Bit)
• macOs 12.6.5 (21G531)

Steps to Reproduce

• Open https://raw.githack.com/MithrilJS/mithril.js/master/examples/editor/index.html
• Type some text into the left column
• on the right hand side every typed character together with "Type on the left panel and see the result on the right panel" is displayed (see attached screenshot)

Expected Behavior

• on the right hand side only the entered text should be displayed as HTML

[tbreuss]

Fixed with #2848