Created nlohmann::basic_json::basic_json (markdown)

nlohmann::basic_json::basic_json.md

@@ -0,0 +1,44 @@
+```cpp
+basic_json();
+basic_json(std::nullptr_t);                           // 1
+```
+```cpp
+basic_json(const value_t t);                          // 2
+```
+```cpp
+basic_json(const T& value);                           // 3
+```
+```cpp
+basic_json(std::initializer_list<basic_json> init);   // 4
+```
+
+## Description
+
+1. Creates a null object.
+2. Creates a default-initialized container of a specified type.
+3. Creates a value-initialized container of an implicitly specified type.
+4. Creates an array or object type from an initializer list.
+
+In case of item 3 and 4, the following types are valid:
+
+| Value type | Type `T`            | Literal |
+| ---------- | --------------------- | ---- |
+| null       | `std::nullptr_t` | `nullptr` |
+| boolean    | any value convertible to `BooleanType` (e.g., `bool`) | `true`, `false` |
+| string     | any value convertible to `StringType` (e.g., `std::string`, `const char *`) | `"hello"` |
+| number     | any value convertible to `NumberIntegerType` (e.g., `int`, `unsigned int`, `long`, `int64_t`) | `10`, `-23e-23`, `3.1415926` |
+| object     | any associative container whose `key_type` is convertible to `StringType` and whose `value_type` is convertible to `basic_json` with the rules described above (e.g., `std::map<std::string, basic_json>`, `std::unordered_map<std::string, int>` | `{{"one", 1}, {"two", 2}}` |
+| array      | any container whose `value_type` is convertible to `basic_json` with the rules described above (e.g., `std::vector<basic_json>`, `std::list<std::string>` | {1, false, "hello"} |
+
+## Parameters
+
+- `t`: type name; can be `null`, `object`, `array`, `string`, `boolean`, `number_integer`, or `number_float`.
+- `value`: can be any value whose type can be translated to a JSON container (see table above).
+- `init`: an initializer list of (a) values that can be translated to a JSON container (see table above) to create an array; (b) pairs of a string type and a value that can be translate to a JSON container (see table above) to create an object.
+
+## Complexity
+
+1. Constant.
+2. Constant.
+3. Linear in the passed value.
+4. Linear in the size of the initializer list.