Add note about --exclude-file in README and update help text

README.rst

@@ -51,6 +51,10 @@ The ``-I`` flag can be used for a list of certain words to allow that are in the
 
 The ``-L`` flag can be used to allow certain words that are comma-separated placed immediately after it.  **Important note:** The list passed to ``-L`` is case-sensitive based on how it is listed in the codespell dictionaries. ::
 
+    codespell -x FILE, --exclude-file=FILE
+
+Ignore whole lines that match those in ``FILE``.  The lines in ``FILE`` should match the to-be-excluded lines exactly.
+
     codespell -S, --skip=
 
 Comma-separated list of files to skip. It accepts globs as well.  Examples:

codespell_lib/_codespell.py

@@ -343,8 +343,9 @@ def parse_options(args):
                              'you\'d give "*.eps,*.txt" to this option.')
 
     parser.add_argument('-x', '--exclude-file', type=str, metavar='FILE',
-                        help='FILE with lines that should not be checked for '
-                             'errors or changed')
+                        help='ignore whole lines that match those '
+                             'in the file FILE. The lines in FILE '
+                             'should match the to-be-excluded lines exactly')
 
     parser.add_argument('-i', '--interactive',
                         action='store', type=int, default=0,