docs: fix changelog PR link
### Added
- Added `Debug` and `PartialEq` implementations for `PromiseError`. [PR 728](https://github.com/near/near-sdk-rs/pull/728).
-- Added convenience function `env::block_timestamp_ms` to return ms since 1970. [PR 736](https://github.com/near/near-sdk-rs/pull/728)
+- Added convenience function `env::block_timestamp_ms` to return ms since 1970. [PR 736](https://github.com/near/near-sdk-rs/pull/736)
- Added an optional way to handle contract errors with `Result`. [PR 745](https://github.com/near/near-sdk-rs/pull/745), [PR 754](https://github.com/near/near-sdk-rs/pull/754) and [PR 757](https://github.com/near/near-sdk-rs/pull/757).
- Added support for using `#[callback_result]` with a function that doesn't have a return. [PR 738](https://github.com/near/near-sdk-rs/pull/738)
- Support for multi-architecture docker builds and updated Rust version to 1.56 with latest [contract builder](https://hub.docker.com/r/nearprotocol/contract-builder). [PR 751](https://github.com/near/near-sdk-rs/pull/751)
