Update documentation to specify no_prelude

Author: Nemo157

src/doc/reference.md

@@ -1885,8 +1885,7 @@ type int8_t = i8;
 
 ### Module-only attributes
 
-- `no_implicit_prelude` - disable injecting `use std::prelude::*` in this
-  module.
+- `no_prelude` - disable injecting `use std::prelude::*` in this module.
 - `path` - specifies the file to load the module from. `#[path="foo.rs"] mod
   bar;` is equivalent to `mod bar { /* contents of foo.rs */ }`. The path is
   taken relative to the directory that the current module is in.