Update changelog on main for #168

Author: phil-opp

Changelog.md

@@ -24,6 +24,10 @@
 - Rewrite for UEFI support ([#130](https://github.com/rust-osdev/bootloader/pull/130))
   - Includes a new build process that no longer uses the `bootimage` crate. See the Readme for details. 
 
+# 0.9.18 _(hotfix)_ – 2021-05-20
+
+- Fix nightly regression by manually passing --gc-sections ([#168](https://github.com/rust-osdev/bootloader/pull/168))
+
 # 0.9.17 _(backport)_ – 2021-04-30
 
 - Reduce the number of used unstable features of x86_64 crate (backport [#155](https://github.com/rust-osdev/bootloader/pull/140))