fix: mermaid rendering broken after rehype-pretty-code bump (closes #638)

Jacky Zhao

2023-12-19 443cd53a1acf33ac0aaa34e0e75760d3da912d18

 quartz/util/lang.ts

@@ -5,3 +5,7 @@
    return `${count} ${s}s`
  }
}

export function capitalize(s: string): string {
  return s.substring(0, 1).toUpperCase() + s.substring(1)
}