INSTALL.txt: s/mingw64/mingw-w64/

INSTALL.txt

@@ -4,10 +4,10 @@ To compile and install SDL:
     1.  Windows with Visual Studio:
         * Read ./docs/README-visualc.md
 
-        Windows building with mingw64 for x86:
+        Windows building with mingw-w64 for x86:
         * Run: cmake -S . -B build -DCMAKE_TOOLCHAIN_FILE=build-scripts/cmake-toolchain-mingw64-i686.cmake && cmake --build build && cmake --install build
 
-        Windows building with mingw64 for x64:
+        Windows building with mingw-w64 for x64:
         * Run: cmake -S . -B build -DCMAKE_TOOLCHAIN_FILE=build-scripts/cmake-toolchain-mingw64-x86_64.cmake && cmake --build build && cmake --install build
 
         macOS with Xcode: