Reorganize directories (#3462)

* 🚚 move files
* 🚚 rename doc folder to docs
* 🚚 rename test folder to tests

docs/examples/merge_patch.cpp

@@ -0,0 +1,40 @@
+#include <iostream>
+#include <nlohmann/json.hpp>
+#include <iomanip> // for std::setw
+
+using json = nlohmann::json;
+
+int main()
+{
+    // the original document
+    json document = R"({
+                "title": "Goodbye!",
+                "author": {
+                    "givenName": "John",
+                    "familyName": "Doe"
+                },
+                "tags": [
+                    "example",
+                    "sample"
+                ],
+                "content": "This will be unchanged"
+            })"_json;
+
+    // the patch
+    json patch = R"({
+                "title": "Hello!",
+                "phoneNumber": "+01-123-456-7890",
+                "author": {
+                    "familyName": null
+                },
+                "tags": [
+                    "example"
+                ]
+            })"_json;
+
+    // apply the patch
+    document.merge_patch(patch);
+
+    // output original and patched document
+    std::cout << std::setw(4) << document << std::endl;
+}