C++20 is necessary

Author: ogoffart

README.md

@@ -13,7 +13,7 @@ C++ code, how to trigger react to callbacks, get and set properties and use basi
 In order to use this template and build a C++ application, you need to install a few tools:
 
   * **[cmake](https://cmake.org/download/)** (3.19 or newer)
-  * A C++ compiler that supports C++ version 17 or newer
+  * A C++ compiler that supports C++ 20 
 
 If your target environment is Linux or Windows on an x86-64 architecture, then you may also opt into downloading one of our binary Slint packages. These are pre-compiled and require no further tools. You can find setup instructions and download links at
 
@@ -52,4 +52,4 @@ We recommend using an IDE for development, along with our [LSP-based IDE integra
 ## Next Steps
 
 We hope that this template helps you get started and you enjoy exploring making user interfaces with Slint. To learn more
-about the Slint APIs and the `.slint` markup language check out our [online documentation](https://slint-ui.com/docs/cpp/).
+about the Slint APIs and the `.slint` markup language check out our [online documentation](https://slint-ui.com/docs/cpp/).