Change description of unnecessary mut passed lint

README.md

@@ -63,7 +63,7 @@ name
 [type_complexity](https://github.com/Manishearth/rust-clippy/wiki#type_complexity)                     | warn    | usage of very complex types; recommends factoring out parts into `type` definitions
 [unicode_not_nfc](https://github.com/Manishearth/rust-clippy/wiki#unicode_not_nfc)                     | allow   | using a unicode literal not in NFC normal form (see http://www.unicode.org/reports/tr15/ for further information)
 [unit_cmp](https://github.com/Manishearth/rust-clippy/wiki#unit_cmp)                                   | warn    | comparing unit values (which is always `true` or `false`, respectively)
-[unnecessary_mut_passed](https://github.com/Manishearth/rust-clippy/wiki#unnecessary_mut_passed)       | warn    | an argument is passed as a mutable reference although the function only demands an immutable reference
+[unnecessary_mut_passed](https://github.com/Manishearth/rust-clippy/wiki#unnecessary_mut_passed)       | warn    | an argument is passed as a mutable reference although the function/method only demands an immutable reference
 [unused_collect](https://github.com/Manishearth/rust-clippy/wiki#unused_collect)                       | warn    | `collect()`ing an iterator without using the result; this is usually better written as a for loop
 [while_let_loop](https://github.com/Manishearth/rust-clippy/wiki#while_let_loop)                       | warn    | `loop { if let { ... } else break }` can be written as a `while let` loop
 [wrong_pub_self_convention](https://github.com/Manishearth/rust-clippy/wiki#wrong_pub_self_convention) | allow   | defining a public method named with an established prefix (like "into_") that takes `self` with the wrong convention