doc(favicon): add documentation of favicon plugin (#1948)

* doc(favicon): add documentation of favicon plugin

* doc(favicon): add missing link to configuration page

* fix(favicon): build on public folder don't created

quartz/plugins/emitters/favicon.ts

@@ -1,16 +1,22 @@
 import sharp from "sharp"
-import { joinSegments, QUARTZ, FilePath } from "../../util/path"
+import { joinSegments, QUARTZ, FullSlug } from "../../util/path"
 import { QuartzEmitterPlugin } from "../types"
+import { write } from "./helpers"
+import { BuildCtx } from "../../util/ctx"
 
 export const Favicon: QuartzEmitterPlugin = () => ({
   name: "Favicon",
   async *emit({ argv }) {
     const iconPath = joinSegments(QUARTZ, "static", "icon.png")
-    const dest = joinSegments(argv.output, "favicon.ico") as FilePath
 
-    await sharp(iconPath).resize(48, 48).toFormat("png").toFile(dest)
+    const faviconContent = sharp(iconPath).resize(48, 48).toFormat("png")
 
-    yield dest
+    yield write({
+      ctx: { argv } as BuildCtx,
+      slug: "favicon" as FullSlug,
+      ext: ".ico",
+      content: faviconContent,
+    })
   },
   async *partialEmit() {},
 })