update ignore file

.gitignore

 ### C++ ###
+
+# build folder
+build
+
+# content folder
+content
+
 # Prerequisites
 *.d
 
@@ -20,6 +27,7 @@
 *.lib
 
 ### CMake ###
+CMakeLists.txt
 CMakeLists.txt.user
 CMakeCache.txt
 CMakeFiles