Fix README and add a test so it won't happen again

tests/test_readme.py

@@ -0,0 +1,19 @@
+from pathlib import Path
+
+
+def test_readme():
+    with open('README.md') as f:
+        readme = f.read()
+
+        bundled = Path(__file__).parent.parent \
+            .joinpath('thefuck') \
+            .joinpath('rules') \
+            .glob('*.py')
+
+        for rule in bundled:
+            if rule.stem != '__init__' and rule.stem not in readme:
+                raise Exception('Missing rule "{}" in README.md'.format(rule.stem))
+
+
+if __name__ == '__main__':
+    test_readme()