Update Changelog to include #309

Signed-off-by: Joe Richey <[email protected]>

Author: josephlr

Changelog.md

@@ -1,5 +1,11 @@
 # Unreleased
 
+- New `registers::segmentation` module ([#309](https://github.com/rust-osdev/x86_64/pull/309)), containing:
+  - `instructions::segmentation::{Segment, Segment64, CS, DS, ES, FS, GS, SS}`
+  - `structures::gdt::SegmentSelector`
+  - Old locations still re-export all the types, so this is not a breaking change.
+- Fixes build so that `cargo doc --no-default-features` succeeds.
+
 # 0.14.5 – 2021-09-04
 
 - Add `ExceptionVector` enum and additional flags to `PageFaultErrorCode` ([#303](https://github.com/rust-osdev/x86_64/pull/303))