Add documentation to the components and layouts.

source/components/page-header/page-header.tsx

@@ -1,13 +1,20 @@
 import "./page-header.scss";
 
+/** Properties for the {@linkcode PageHeader} component. */
 type Props = {
+  /** Whether this header should use the full width and height of the viewport. */
   fullPage?: boolean;
+  /** The `alt` attribute to use for the logo `<img>`. */
   logoAlt?: string;
+  /** The `src` attribute to use for the logo `<img>`. */
   logoSrc?: string;
+  /** The subtitle to put beneath the `<h1>`. */
   subtitle?: string;
+  /** The text for the `<h1>`. */
   title?: string;
 };
 
+/** Shared header component for all pages. */
 export function PageHeader(props: Props): JsxElement {
   const {fullPage, logoAlt, logoSrc, subtitle, title} = props;
 

source/layouts/base.astro

@@ -1,9 +1,16 @@
 ---
 import "../scss/common.scss";
 
+/** Properties for the base layout. */
 interface Props {
+  /** MDX frontmatter. */
   frontmatter: {
+    /**
+     * Path to an image to use as the favicon, defaults to the Tildes Community
+     * logo.
+     */
     favicon?: string;
+    /** The text to use for the `<title>` element. */
     pageTitle: string;
   };
 }