fix typo in docs
nom no longer relies on macros, but an exclamation mark was left over
//! - **`many0`**: Will apply the parser 0 or more times (if it returns the `O` type, the new parser returns `Vec<O>`)
//! - **`many1`**: Will apply the parser 1 or more times
//!
-//! There are more complex (and more useful) parsers like `tuple!`, which is
+//! There are more complex (and more useful) parsers like `tuple`, which is
//! used to apply a series of parsers then assemble their results.
//!
//! Example with `tuple`:
