Convert examples to piecemeal includes

examples/300-Gen-OwnGenerator.cpp

@@ -4,7 +4,9 @@
 // Specifically we will implement a random number generator for integers
 // It will have infinite capacity and settable lower/upper bound
 
-#include <catch2/catch.hpp>
+#include <catch2/catch_test_macros.hpp>
+#include <catch2/catch_generators.hpp>
+#include <catch2/catch_generators_generic.hpp>
 
 #include <random>