fix: handle 3+ word Options: section names

parse_defaults() was failing with an AssertionError when an options
section with 3 or more words was used. e.g. "Very Advanced Options:".

This fixes #9

docopt/__init__.py

@@ -711,9 +711,7 @@ def parse_defaults(docstring: str) -> list[Option]:
     defaults = []
     for s in parse_section("options:", docstring):
         options_literal, _, s = s.partition(":")
-        if " " in options_literal:
-            _, _, options_literal = options_literal.partition(" ")
-        assert options_literal.lower().strip() == "options"
+        assert options_literal.lower().endswith("options")
         split = re.split(r"\n[ \t]*(-\S+?)", "\n" + s)[1:]
         split = [s1 + s2 for s1, s2 in zip(split[::2], split[1::2])]
         for s in split:

tests/test_docopt.py

@@ -648,6 +648,7 @@ def test_language_errors():
     [
         pytest.param("Usage: prog\n  Options:  --foo\n"),
         pytest.param("Usage: prog\n  Advanced Options:  --foo\n"),
+        pytest.param("Usage: prog\n  Very Advanced Options:  --foo\n"),
     ],
 )
 def test_docopt_reports_options_in_usage_section(doc: str):