Update CHANGELOG.md. Tag v0.3.1.

Author: cr1901

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
+## [v0.3.0]- 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
@@ -18,6 +20,11 @@ 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
+- 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
 - [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).
@@ -149,7 +156,8 @@ Initial release
 [`r0`]: https://github.com/rust-embedded/r0
 [`cortex-m-rt`]: https://github.com/japaric/cortex-m-rt
 
-[Unreleased]: https://github.com/rust-embedded/msp430-rt/compare/msp_v0.3.0...HEAD
+[Unreleased]: https://github.com/rust-embedded/msp430-rt/compare/msp_v0.3.1...HEAD
+[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
 [v0.2.4]: https://github.com/rust-embedded/msp430-rt/compare/msp_v0.2.3...msp_v0.2.4