feat(comments): conditional display via frontmatter (#1566)

quartz/components/Comments.tsx

@@ -25,7 +25,14 @@ function boolToStringBool(b: boolean): string {
 }
 
 export default ((opts: Options) => {
-  const Comments: QuartzComponent = ({ displayClass, cfg }: QuartzComponentProps) => {
+  const Comments: QuartzComponent = ({ displayClass, fileData, cfg }: QuartzComponentProps) => {
+    // check if comments should be displayed according to frontmatter
+    const commentsFlag: boolean =
+      fileData.frontmatter?.comments === true || fileData.frontmatter?.comments === "true"
+    if (!commentsFlag) {
+      return <></>
+    }
+
     return (
       <div
         class={classNames(displayClass, "giscus")}