Rename COPYING -> LICENSE

Author: yhabteab

CMakeLists.txt

@@ -94,7 +94,7 @@ endif()
 
 set(ICINGA2_BUILD_COMPILER_VERSION "${CMAKE_CXX_COMPILER_VERSION}")
 
-file(READ "${CMAKE_CURRENT_SOURCE_DIR}/COPYING" ICINGA2_LICENSE_GPL)
+file(READ "${CMAKE_CURRENT_SOURCE_DIR}/LICENSE" ICINGA2_LICENSE_GPL)
 set(ICINGA2_LICENSE "${ICINGA2_LICENSE_GPL}\n\n---\n\n${ICINGA2_LICENSE_ADDITIONS}")
 file(WRITE "${CMAKE_CURRENT_BINARY_DIR}/LICENSE.txt" ${ICINGA2_LICENSE})