📝 added example and documentation for the meta function

doc/examples/meta.cpp

+#include <json.hpp>
+
+using json = nlohmann::json;
+
+int main()
+{
+    // call meta()
+    std::cout << std::setw(4) << json::meta() << '\n';
+}

doc/examples/meta.link

+<a target="_blank" href="http://melpon.org/wandbox/permlink/3hERJociqLo3vdod"><b>online</b></a>
\ No newline at end of file

doc/examples/meta.output

+{
+    "compiler": {
+        "c++": "201103",
+        "family": "clang",
+        "version": "8.0.0 (clang-800.0.42.1)"
+    },
+    "copyright": "(C) 2013-2017 Niels Lohmann",
+    "name": "JSON for Modern C++",
+    "platform": "apple",
+    "url": "https://github.com/nlohmann/json",
+    "version": {
+        "major": 2,
+        "minor": 1,
+        "patch": 0,
+        "string": "2.1.0"
+    }
+}

src/json.hpp

@@ -1105,6 +1105,26 @@ class basic_json
 
     /*!
     @brief returns version information on the library
+
+    This function returns a JSON object with infiormation about the library,
+    including the version number and information on the platform and compiler.
+
+    @return JSON object holding version information
+    key         | description
+    ----------- | ---------------
+    `compiler`  | Information on the used compiler. It is an object with the following keys: `c++` (the used C++ standard), `family` (the compiler family; possible values are `clang`, `icc`, `gcc`, `ilecpp`, `msvc`, `pgcpp`, `sunpro`, and `unknown`), and `version` (the compiler version).
+    `copyright` | The copyright line for the library as string.
+    `name`      | The name of the library as string.
+    `platform`  | The used platform as string. Possible values are `win32`, `linux`, `apple`, `unix`, and `unknown`.
+    `url`       | The URL of the project as string.
+    `version`   | The version of the library. It is an object with the following keys: `major`, `minor`, and `patch` as defined by [Semantic Versioning](http://semver.org), and `string` (the version string).
+
+    @liveexample{The following code shows an example output of the `meta()`
+    function.,meta}
+
+    @complexity Constant.
+
+    @since 2.1.0
     */
     static basic_json meta()
     {
@@ -8059,7 +8079,7 @@ class basic_json
     @liveexample{The following code exemplifies `type_name()` for all JSON
     types.,type_name}
 
-    @since version 1.0.0
+    @since version 1.0.0, public since 2.1.0
     */
     std::string type_name() const
     {

src/json.hpp.re2c

@@ -1105,6 +1105,26 @@ class basic_json
 
     /*!
     @brief returns version information on the library
+
+    This function returns a JSON object with infiormation about the library,
+    including the version number and information on the platform and compiler.
+
+    @return JSON object holding version information
+    key         | description
+    ----------- | ---------------
+    `compiler`  | Information on the used compiler. It is an object with the following keys: `c++` (the used C++ standard), `family` (the compiler family; possible values are `clang`, `icc`, `gcc`, `ilecpp`, `msvc`, `pgcpp`, `sunpro`, and `unknown`), and `version` (the compiler version).
+    `copyright` | The copyright line for the library as string.
+    `name`      | The name of the library as string.
+    `platform`  | The used platform as string. Possible values are `win32`, `linux`, `apple`, `unix`, and `unknown`.
+    `url`       | The URL of the project as string.
+    `version`   | The version of the library. It is an object with the following keys: `major`, `minor`, and `patch` as defined by [Semantic Versioning](http://semver.org), and `string` (the version string).
+
+    @liveexample{The following code shows an example output of the `meta()`
+    function.,meta}
+
+    @complexity Constant.
+
+    @since 2.1.0
     */
     static basic_json meta()
     {
@@ -8059,7 +8079,7 @@ class basic_json
     @liveexample{The following code exemplifies `type_name()` for all JSON
     types.,type_name}
 
-    @since version 1.0.0
+    @since version 1.0.0, public since 2.1.0
     */
     std::string type_name() const
     {