Filter entities by name when extracting data from Arkindex

Closes #134 (closed)

dan/datasets/extract/__init__.py

@@ -100,7 +100,11 @@ def add_extract_parser(subcommands) -> None:
         "--entity-separators",
         type=validate_char,
         nargs="+",
-        help="Removes all text that does not appear in an entity or in the list of given characters. Do not give any arguments for keeping the whole text.",
+        help="""
+            Removes all text that does not appear in an entity or in the list of given ordered characters.
+            If several separators follow each other, keep only the first to appear in the list.
+            Do not give any arguments to keep the whole text.
+        """,
         required=False,
     )
     parser.add_argument(