Fix API docs example code to pass CI.
//! as necessary:
//!
//! ```
+//! # #[cfg(feature = "napi-1")] {
//! # use neon::prelude::*;
//! fn set_and_check<'a>(
//! cx: &mut impl Context<'a>,
//! ) -> JsResult<'a, JsValue> {
//! let value = cx.string("hello!");
//! // set property "17" with integer shorthand
-//! obj.set(17, value)?;
+//! obj.set(cx, 17, value)?;
//! // get property "17" with string shorthand
//! // returns the same value ("hello!")
-//! obj.get("17")
+//! obj.get(cx, "17")
//! }
+//! # }
//! ```
//!
//! [hierarchy]: crate::types#the-javascript-type-hierarchy
