Update CHANGELOG.md. Tag v0.4.0.

Author: cr1901

CHANGELOG.md

@@ -7,9 +7,21 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
-## [v0.3.0]- 2022-02-19
+## [v0.4.0]- 2022-09-11
 
-## Added
+### Changed
+- Update [`msp430`] crate from `0.3.0` to `0.4.0`. This crate remains
+  API-compatible with [v0.3.1]. Updating [`msp430`] is _transitively_ a
+  breaking change due to previously always-enabled functionality now being
+  gated behind the default-disabled `critical-section-single-core` feature.
+
+### Fixed
+- `trybuild` tests with outdated messages were updated or removed as
+  appropriate.
+
+## [v0.3.1]- 2022-02-19
+
+### Added
 - The `entry` attribute macro for main can now take an `interrupt_enable`
   argument. The `interrupt_enable` argument will enable interrupts before
   calling the function with the `entry` attribute, possibly calling an an
@@ -20,12 +32,12 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
   - Use [GHA](https://github.com/rust-embedded/msp430-rt/actions) for these UI
     tests.
 
-## Changed
+### Changed
 - Nested functions generated by the `entry` and `interrupt` macros have the
   `inline(always)` attribute applied to them. This in fact saves space and
   execution time by removing a call/jump into the nested function body.
 
-## Fixed
+### Fixed
 - [docs.rs](https://docs.rs) [metadata](https://docs.rs/about/metadata) added
   to `Cargo.toml` to fix documentation building [failure](https://github.com/rust-embedded/msp430-rt/issues/16).
 - Change instances of `msp430_macros` in docs to correct `msp430_rt_macros`
@@ -155,8 +167,10 @@ Initial release
 
 [`r0`]: https://github.com/rust-embedded/r0
 [`cortex-m-rt`]: https://github.com/japaric/cortex-m-rt
+[`msp430`]: https://github.com/rust-embedded/msp430
 
-[Unreleased]: https://github.com/rust-embedded/msp430-rt/compare/msp_v0.3.1...HEAD
+[Unreleased]: https://github.com/rust-embedded/msp430-rt/compare/msp_v0.4.0...HEAD
+[v0.4.0]: https://github.com/rust-embedded/msp430-rt/compare/msp_v0.3.1...msp_v0.4.0
 [v0.3.1]: https://github.com/rust-embedded/msp430-rt/compare/msp_v0.3.0...msp_v0.3.1
 [v0.3.0]: https://github.com/rust-embedded/msp430-rt/compare/msp_v0.2.5...msp_v0.3.0
 [v0.2.5]: https://github.com/rust-embedded/msp430-rt/compare/msp_v0.2.4...msp_v0.2.5