Don't add Breaking headings for single breaking change

Author: phil-opp

Changelog.md

@@ -1,13 +1,8 @@
 # 0.6.0
 
-## Breaking
-
-- Don't set the `#[cfg(not(test))]` attribute for the entry point function in the `entry_point` macro
+- **Breaking**: Don't set the `#[cfg(not(test))]` attribute for the entry point function in the `entry_point` macro
     - With custom test frameworks, it's possible to use the normal entry point also in test environments
     - To get the old behavior, you can add the `#[cfg(not(test))]` attribute to the `entry_point` invocation
-
-## Other
-
 - Additional assertions for the passed `KERNEL` executable
     - check that the executable exists (for better error messages)
     - check that the executable has a non-empty text section (an empty text section occurs when no entry point is set)
@@ -26,9 +21,7 @@
 
 # 0.5.0
 
-## Breaking
-
-- Change the build system: Use a build script that expects a `KERNEL` environment variable instead of using a separate `builder` executable as before. See [#51](https://github.com/rust-osdev/bootloader/pull/51) and [#53](https://github.com/rust-osdev/bootloader/pull/53) for more information.
+- **Breaking**: Change the build system: Use a build script that expects a `KERNEL` environment variable instead of using a separate `builder` executable as before. See [#51](https://github.com/rust-osdev/bootloader/pull/51) and [#53](https://github.com/rust-osdev/bootloader/pull/53) for more information.
   - This makes the bootloader incompatible with versions `0.6.*` and earlier of the `bootimage` tool.
   - The bootloader also requires the `llvm-tools-preview` rustup component now.