bug(schemars_derive/docs): newlines get stripped in example blocks

[DonIsaac]

use schemars::JsonSchema;
use serde::Deserialize;

/// # Some Config
/// 
/// This config does some stuff.
///
/// # Example
///
/// ```jsonc
/// {
///   // use this config setting in a certain way
///   "foo": ["bar", "baz"],
/// }
/// ```
#[derive(Debug, Deserialize, Default, JSONSchema)]
pub struct Config {
    foo: Vec<String>
}

When rendered to a JSON schema, the code block in the schema's description field will be stripped, causing invalid JSONC to be rendered. It looks like other markdown in description has its whitespace preserved.

[GREsau]

Duplicate of #38 / #120 / #129

Fortunately, this is now fixed in schemars v1.0.0-alpha.3