Clean up and document project files (#4560)

docs/mkdocs/docs/examples/get_ptr.cpp

@@ -0,0 +1,21 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // create a JSON number
+    json value = 17;
+
+    // explicitly getting pointers
+    auto p1 = value.get_ptr<const json::number_integer_t*>();
+    auto p2 = value.get_ptr<json::number_integer_t*>();
+    auto p3 = value.get_ptr<json::number_integer_t* const>();
+    auto p4 = value.get_ptr<const json::number_integer_t* const>();
+    auto p5 = value.get_ptr<json::number_float_t*>();
+
+    // print the pointees
+    std::cout << *p1 << ' ' << *p2 << ' ' << *p3 << ' ' << *p4 << '\n';
+    std::cout << std::boolalpha << (p5 == nullptr) << '\n';
+}