Clean up and document project files (#4560)

docs/mkdocs/docs/examples/to_msgpack.cpp

@@ -0,0 +1,22 @@
+#include <iostream>
+#include <iomanip>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+using namespace nlohmann::literals;
+
+int main()
+{
+    // create a JSON value
+    json j = R"({"compact": true, "schema": 0})"_json;
+
+    // serialize it to MessagePack
+    std::vector<std::uint8_t> v = json::to_msgpack(j);
+
+    // print the vector content
+    for (auto& byte : v)
+    {
+        std::cout << "0x" << std::hex << std::setw(2) << std::setfill('0') << (int)byte << " ";
+    }
+    std::cout << std::endl;
+}