Update readme.md

Author: dobrakmato

readme.md

@@ -1037,6 +1037,7 @@
 | [Whimsical](https://whimsical.com/)| Wireframes, diagrams and more (4 free) |
 | [Whiteboard](https://witeboard.com/)| Online drawing tool |
 | [Octopus](https://octopus.do/)| Sitemap builder |
+| [Onlineboard](https://onlineboard.eu)| Real-time shareable whiteboard for brainstorming |
 | [CTA Button Maker](https://www.clickminded.com/button-generator/)| Create call to action buttons |
 | [Blobmaker](https://www.blobmaker.app/)| Blobmaker is a free generative design tool, to help you quickly create random, unique, and organic-looking SVG shapes.  |
 | [Personas](https://personas.draftbit.com/)| A playful avatar generator for the modern age  |