feat: support custom canonical URLs (#83)

Adding an optional attribute in the posts' frontmatter that allows the user to set a custom canonical URL

src/layouts/Layout.astro

@@ -9,6 +9,7 @@ export interface Props {
   author?: string;
   description?: string;
   ogImage?: string;
+  canonicalURL?: string;
 }
 
 const {
@@ -16,10 +17,9 @@ const {
   author = SITE.author,
   description = SITE.desc,
   ogImage = SITE.ogImage,
+  canonicalURL = new URL(Astro.url.pathname, Astro.site).href,
 } = Astro.props;
 
-const canonicalURL = new URL(Astro.url.pathname, Astro.site);
-
 const socialImageURL = new URL(
   ogImage ? ogImage : SITE.ogImage,
   Astro.url.origin

src/layouts/PostDetails.astro

@@ -13,7 +13,7 @@ export interface Props {
 
 const { post } = Astro.props;
 
-const { title, author, description, ogImage, pubDatetime, tags } = post.data;
+const { title, author, description, ogImage, canonicalURL, pubDatetime, tags } = post.data;
 
 const { Content } = await post.render();
 
@@ -21,7 +21,7 @@ const ogUrl = new URL(ogImage ? ogImage : `${title}.png`, Astro.url.origin)
   .href;
 ---
 
-<Layout title={title} author={author} description={description} ogImage={ogUrl}>
+<Layout title={title} author={author} description={description} ogImage={ogUrl} canonicalURL={canonicalURL}>
   <Header />
   <div class="mx-auto flex w-full max-w-3xl justify-start px-2">
     <button