fixed whitelisting description

README.rst

@@ -66,7 +66,7 @@ Whitelisting
 False positives can happen so there is a whitelist feature to fix them shorthand.
 You can either add entries to the default whitelist with ``--whitelist-extend`` or overwrite the default with ``--whitelist``.
 Both arguments expect a string of ``#`` separated regex strings (whitespaces are preserved). E.g. ``eradicate --whitelist "foo#b a r" filename``
-Those regex strings are matched against the start of the comment itself.
+Those regex strings are matched case insensitive against the start of the comment itself.
 
 For the default whitelist please see ``eradicate.py``.