projects: CMake: bump up minimal raylib version (#983)

While at it, add comment to indicate what the version signifies.

[a3f: updated commit message]

projects/CMake/CMakeLists.txt

@@ -1,7 +1,8 @@
 cmake_minimum_required(VERSION 3.11) # FetchContent is available in 3.11+
 project(example)
 
-find_package(raylib 2.0 QUIET) # Let CMake search for a raylib-config.cmake
+# Set this to the minimal version you want to support
+find_package(raylib 2.5 QUIET) # Let CMake search for a raylib-config.cmake
 
 # You could change the QUIET above to REQUIRED and remove this if() clause
 # This part downloads raylib and builds it if it's not installed on your system