added the cwk_path_change_root function

docs/reference/cwk_path_change_root.md

@@ -0,0 +1,69 @@
+---
+title: cwk_path_change_root
+description: Changes the root of a path.
+---
+
+_(since v1.2.0)_  
+Changes the root of a path.
+
+## Description
+```c
+size_t cwk_path_change_root(const char *path, const char *new_root,
+  char *buffer, size_t buffer_size);
+```
+
+This function changes the root of a path. It does not normalize the result.
+The result will be written to a buffer, which might be truncated if the
+buffer is not large enough to hold the full path. However, the truncated
+result will always be null-terminated. The returned value is the amount of
+characters which the resulting path would take if it was not truncated
+(excluding the null-terminating character).
+
+**Note:** This function does not normalize the resulting path. You can use 
+**[cwk_path_normalize]({{ site.baseurl }}{% link reference/cwk_path_normalize.md %})**
+to do so. The new root may contain separators which will introduce new segments. 
+If the submitted path does not have any segments, the basename will be appended 
+as a new segment.
+
+## Parameters
+ * **path**: The original path which will get a new root.
+ * **new_root**: The new root which will be placed in the path.
+ * **buffer**: The output buffer where the result is written to.
+ * **buffer_size**: The size of the output buffer where the result is written 
+ to.
+
+## Return Value
+Returns the total amount of characters of the new path.
+
+## Example
+```c
+#include <cwalk.h>
+#include <stdio.h>
+#include <stddef.h>
+#include <stdlib.h>
+
+int main(int argc, char *argv[])
+{
+  char buffer[FILENAME_MAX];
+
+  cwk_path_set_style(CWK_STYLE_WINDOWS);
+
+  cwk_path_change_root("C:\\test.txt", "D:\\", buffer,
+    sizeof(buffer));
+
+  printf("The new path: '%s'", buffer);
+
+  return EXIT_SUCCESS;
+}
+```
+
+Ouput:
+```
+The new path: 'D:\another.txt'
+```
+
+## Changelog
+
+| Version    | Description                                            |
+|------------|--------------------------------------------------------|
+| **v1.2.0** | The function is introduced.                            |

docs/reference/index.md

@@ -19,6 +19,9 @@ Gets the dirname of a file path.
 * **[cwk_path_get_root]({{ site.baseurl }}{% link reference/cwk_path_get_root.md %})**  
 Determines the root of a path.
 
+* **[cwk_path_change_root]({{ site.baseurl }}{% link reference/cwk_path_change_root.md %})**  
+Changes the root of a path.
+
 * **[cwk_path_is_absolute]({{ site.baseurl }}{% link reference/cwk_path_is_absolute.md %})**  
 Determine whether the path is absolute or not.