doc: add CI badge

Author: felipe-iar

README.md

@@ -1,5 +1,7 @@
 # Building CMake projects with IAR
 
+[![CI](https://github.com/iarsystems/cmake-tutorial/actions/workflows/ci.yml/badge.svg)](https://github.com/iarsystems/cmake-tutorial/actions/workflows/ci.yml)
+
 CMake is an open-source, cross-platform family of tools maintained and supported by Kitware. Among its many features, it essentially provides [Makefile Generators](https://cmake.org/cmake/help/latest/manual/cmake-generators.7.html#id11) and [Ninja Generators](https://cmake.org/cmake/help/latest/manual/cmake-generators.7.html#id12) which compose scripts for cross-compiling C/C++ embedded software projects based on one or more `CMakeLists.txt` configuration files.
 
 This tutorial offers a short introduction for those seeking information on how to start using the IAR C/C++ Compiler together with CMake from the command line. While this guide is based on the IAR Build Tools for Arm (CXARM) 9.60.4 on Linux, it should work with other supported IAR products with no or minimal changes.