Clean up and document project files (#4560)

docs/mkdocs/docs/examples/object_comparator_t.cpp

@@ -0,0 +1,11 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    std::cout << std::boolalpha
+              << "json::object_comparator_t(\"one\", \"two\") = " << json::object_comparator_t{}("one", "two") << "\n"
+              << "json::object_comparator_t(\"three\", \"four\") = " << json::object_comparator_t{}("three", "four") << std::endl;
+}