Fix some comments regarding what files are symlinked
diff --git a/include/CMakeLists.txt b/include/CMakeLists.txt
index 3081b26..1b581a5 100644
--- a/include/CMakeLists.txt
+++ b/include/CMakeLists.txt
@@ -10,8 +10,7 @@
 
 endif(INSTALL_MBEDTLS_HEADERS)
 
-# Make scripts and data files needed for testing available in an
-# out-of-source build.
+# Make config.h available in an out-of-source build. ssl-opt.sh requires it.
 if (NOT ${CMAKE_CURRENT_BINARY_DIR} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR})
     link_to_source(mbedtls)
 endif()