docs: add docstrings to dated file handler

ref: N25B-401

src/control_backend/logging/dated_file_handler.py

@@ -12,12 +12,21 @@ class DatedFileHandler(FileHandler):
         super().__init__(**kwargs)
 
     def _make_filename(self) -> str:
+        """
+        Create the filename for the current logfile, using the configured file prefix and the
+        current date and time. If the directory does not exist, it gets created.
+
+        :return: A filepath.
+        """
         filepath = Path(f"{self._file_prefix}-{datetime.now():%Y%m%d-%H%M%S}.log")
         if not filepath.parent.is_dir():
             filepath.parent.mkdir(parents=True, exist_ok=True)
         return str(filepath)
 
     def do_rollover(self):
+        """
+        Close the current logfile and create a new one with the current date and time.
+        """
         self.acquire()
         try:
             if self.stream: