📝 add examples for parsing from iterator pair (#3100)

doc/examples/parse__pointers.cpp

@@ -0,0 +1,15 @@
+#include <iostream>
+#include <iomanip>
+#include <nlohmann/json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // a JSON text given as string that is not null-terminated
+    const char* ptr = "[1,2,3]another value";
+
+    // parse and serialize JSON
+    json j_complete = json::parse(ptr, ptr + 7);
+    std::cout << std::setw(4) << j_complete << "\n\n";
+}