Clean up and document project files (#4560)

docs/mkdocs/docs/examples/parse__contiguouscontainer__parser_callback_t.cpp

@@ -0,0 +1,15 @@
+#include <iostream>
+#include <iomanip>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // a JSON text given as std::vector
+    std::vector<std::uint8_t> text = {'[', '1', ',', '2', ',', '3', ']', '\0'};
+
+    // parse and serialize JSON
+    json j_complete = json::parse(text);
+    std::cout << std::setw(4) << j_complete << "\n\n";
+}