Check single-header using test examples

This means that examples build for all matrix entries
diff --git a/CMakeLists.txt b/CMakeLists.txt
index aaa8877..106f23a 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,6 +3,7 @@
 project(CatchSelfTest)
 
 option(USE_VALGRIND "Perform SelfTests with Valgrind" OFF)
+option(BUILD_EXAMPLES "Build documentation examples" OFF)
 
 set_property(GLOBAL PROPERTY USE_FOLDERS ON)