docs: correct comments in example cntlm.conf

see #115

doc/cntlm.conf

@@ -1,8 +1,13 @@
 #
 # Cntlm Authentication Proxy Configuration
 #
-# NOTE: all values are parsed literally, do NOT escape spaces,
-# do not quote. Use 0600 perms if you use plaintext password.
+# NOTE: No URL escape encoding is needed. For example, 123@xyz is
+# parsed literally, do NOT use 123%40xyz where %40 is the encoding
+# of @. In case the password contains special characters like
+# spaces, pound signs, etc, it should be enclosed in double quotes.
+# For examples, 123#xyz should be "123#xyz".
+# Use 0600 perms if you use plaintext password and see cntlm(1) man
+# page for more details.
 #
 
 # Username	testuser