readme mods. can build with glfw in either Debug or Release config. some reorg of the cpp example

examples/cpp/export.bat

@@ -0,0 +1,22 @@
+@ECHO off
+SETLOCAL ENABLEDELAYEDEXPANSION
+
+ECHO [ > compile_commands.json
+
+FOR /r "src\" %%F IN (*.cpp) DO (
+
+SET "file=%%F"
+SET "file=!file:\=/!"
+SET "directory=%~dp0"
+SET "directory=!directory:\=/!"
+
+ECHO { >> compile_commands.json
+ECHO "directory": "!directory!", >> compile_commands.json
+ECHO "command": "cl !file! -I inc -I ../../ext/glm -I ../../ext/glfw/include %flags% -std:c++20 -MD -MP -Fo:obj\\ ", >> compile_commands.json
+
+ECHO "file": "!file!" >> compile_commands.json
+ECHO }, >> compile_commands.json
+
+)
+
+ECHO ] >> compile_commands.json