diff --git a/README.md b/README.md
index d900e53..24c378a 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,9 @@
 This is a roadmap for those who want to build a career as an Embedded Developer or Embedded Engineer.
 In order to assist beginners, steps have been taken to create a roadmap that is straightforward and easy to understand.
 
-If you think that this map can be improved in anyway, please start an issue or pull request. I’ll be maintaining and updating this repository frequently. The source file is created using [Microsoft Visio](https://office.com/visio).
+If you think that this map can be improved in anyway, please start an issue or pull request. I’ll be maintaining and updating this repository frequently.
+
+The source file is created using [Microsoft Visio](https://office.com/visio) in `.vsdx` format and included in this repository for your contributions. If you do not have Microsoft Visio or you want to use free software, you can use [draw.io](https://draw.io) which can import and export `.vsdx` files.
 
 ![Embedded Systems Engineering Roadmap](https://github.com/m3y54m/Embedded-Engineering-Roadmap/releases/download/Rev.F-2023-07-27/Embedded-Engineering-Roadmap.png)