Fix method comment

src/speller2_worker.py

@@ -34,7 +34,7 @@ class Speller2Worker(nlp_ws.NLPWorker):
 
     @classmethod
     def _read_file(cls, input_path):
-        """Reading text from input file"""
+        """Reading text from input file."""
         with open(input_path, 'r', encoding='utf-8') as f:
             content = f.read()