docs: improve md format for `jj fix` #158

Job	Run time
Build binary artifacts (linux-x86_64-musl)	4m 56s
Build binary artifacts (linux-x86_64-gnu)	5m 16s
Build binary artifacts (linux-aarch64-musl)	5m 21s
Build binary artifacts (linux-aarch64-gnu)	5m 4s
Build binary artifacts (macos-x86_64)	8m 30s
Build binary artifacts (macos-aarch64)	3m 49s
Build binary artifacts (win-x86_64)	7m 58s
	40m 54s

Provide feedback