update docs wrt to suggestions

Author: fluiderson

library/std/src/fs.rs

@@ -2803,8 +2803,8 @@ pub fn create_dir<P: AsRef<Path>>(path: P) -> io::Result<()> {
 /// Recursively create a directory and all of its parent components if they
 /// are missing.
 ///
-/// This function returns an error if any of the path components are not a directory and already
-/// exist.
+/// This function is not atomic. If it returns an error, any parent components it was able to create
+/// will remain.
 ///
 /// If the empty path is passed to this function, it always succeeds without
 /// creating any directories.