Fix DOCDIR being fixed to the top level project

packaging/CMakeLists.txt

@@ -77,7 +77,7 @@ install(
     FILES
     "${LIBF2C_SOURCE_DIR}/Notice"
     RENAME copyright
-    DESTINATION "${CMAKE_INSTALL_DOCDIR}"
+    DESTINATION "${CMAKE_INSTALL_DATAROOTDIR}/doc/${PROJECT_NAME}"
     COMPONENT library
 )
 
@@ -85,7 +85,7 @@ install(
     FILES
     "${LIBF2C_SOURCE_DIR}/Notice"
     RENAME copyright
-    DESTINATION "${CMAKE_INSTALL_DOCDIR}"
+    DESTINATION "${CMAKE_INSTALL_DATAROOTDIR}/doc/${PROJECT_NAME}"
     COMPONENT executable
 )