Reorganize directories (#3462)

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

docs/mkdocs/docs/api/basic_json/get_binary.md

@@ -0,0 +1,45 @@
+# <small>nlohmann::basic_json::</small>get_binary
+
+```cpp
+binary_t& get_binary();
+
+const binary_t& get_binary() const;
+```
+
+Returns a reference to the stored binary value.
+
+## Return value
+
+Reference to binary value.
+
+## Exception safety
+
+Strong exception safety: if an exception occurs, the original value stays intact.
+
+## Exceptions
+
+Throws [`type_error.302`](../../home/exceptions.md#jsonexceptiontype_error302) if the value is not binary
+
+## Complexity
+
+Constant.
+
+## Examples
+
+??? example
+
+    The following code shows how to query a binary value.
+     
+    ```cpp
+    --8<-- "examples/get_binary.cpp"
+    ```
+    
+    Output:
+    
+    ```json
+    --8<-- "examples/get_binary.output"
+    ```
+
+## Version history
+
+- Added in version 3.8.0.