doc: minor streamlining

multiboot2-header/README.md

@@ -1,6 +1,5 @@
 # multiboot2-header
 
-![Build](https://github.com/rust-osdev/multiboot2/actions/workflows/rust.yml/badge.svg)
 [![crates.io](https://img.shields.io/crates/v/multiboot2-header.svg)](https://crates.io/crates/multiboot2-header)
 [![docs](https://docs.rs/multiboot2-header/badge.svg)](https://docs.rs/multiboot2-header/)