Reorganize directories (#3462)

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

docs/mkdocs/docs/api/basic_json/patch.md

@@ -0,0 +1,72 @@
+# <small>nlohmann::basic_json::</small>patch
+
+```cpp
+basic_json patch(const basic_json& json_patch) const;
+```
+
+[JSON Patch](http://jsonpatch.com) defines a JSON document structure for expressing a sequence of operations to apply to
+a JSON document. With this function, a JSON Patch is applied to the current JSON value by executing all operations from
+the patch.
+
+## Parameters
+
+`json_patch` (in)
+:   JSON patch document
+
+## Return value
+
+patched document
+
+## Exception safety
+
+Strong guarantee: if an exception is thrown, there are no changes in the JSON value.
+
+## Exceptions
+
+- Throws [`parse_error.104`](../../home/exceptions.md#jsonexceptionparse_error104) if the JSON patch does not consist of
+  an array of objects.
+- Throws [`parse_error.105`](../../home/exceptions.md#jsonexceptionparse_error105) if the JSON patch is malformed (e.g.,
+  mandatory attributes are missing); example: `"operation add must have member path"`.
+- Throws [`out_of_range.401`](../../home/exceptions.md#jsonexceptionout_of_range401) if an array index is out of range.
+- Throws [`out_of_range.403`](../../home/exceptions.md#jsonexceptionout_of_range403) if a JSON pointer inside the patch
+  could not be resolved successfully in the current JSON value; example: `"key baz not found"`.
+- Throws [`out_of_range.405`](../../home/exceptions.md#jsonexceptionout_of_range405) if JSON pointer has no parent
+  ("add", "remove", "move")
+- Throws [`out_of_range.501`](../../home/exceptions.md#jsonexceptionother_error501) if "test" operation was
+  unsuccessful.
+
+## Complexity
+
+Linear in the size of the JSON value and the length of the JSON patch. As usually only a fraction of the JSON value is
+affected by the patch, the complexity can usually be neglected.
+
+## Notes
+
+The application of a patch is atomic: Either all operations succeed and the patched document is returned or an exception
+is thrown. In any case, the original value is not changed: the patch is applied to a copy of the value.
+
+## Examples
+
+??? example
+
+    The following code shows how a JSON patch is applied to a value.
+     
+    ```cpp
+    --8<-- "examples/patch.cpp"
+    ```
+    
+    Output:
+    
+    ```json
+    --8<-- "examples/patch.output"
+    ```
+
+## See also
+
+- [RFC 6902 (JSON Patch)](https://tools.ietf.org/html/rfc6902)
+- [RFC 6901 (JSON Pointer)](https://tools.ietf.org/html/rfc6901)
+- [merge_patch](merge_patch.md) applies a JSON Merge Patch
+
+## Version history
+
+- Added in version 2.0.0.