Make RSS item guid actually unique

Was previously based on the item date, which fails to be unique when
multiple items are committed at the same time.

src/feed.njk

@@ -30,8 +30,8 @@ metadata:
     <item>
       <title>{{ item.data.title }}</title>
       <link>{{ item.data.relativeUrl | absoluteUrl(metadata.url)}}</link>
-      <pubDate>{{ item.date | stringToDate | dateToRfc822 }}</pubDate>
-      <guid isPermaLink="false">{{ item.date | stringToDate | dateToRfc822 }}</guid>
+      <pubDate>{{ item.page.date | stringToDate | dateToRfc822 }}</pubDate>
+      <guid isPermaLink="false">{{item.page.url}}</guid>
       <description>{{ item.content | htmlToAbsoluteUrls(metadata.url) | convertYouTubeURLsToEmbeds }}</description>
     </item>
 

src/feed/duplicate-rss-entries.md

@@ -0,0 +1,11 @@
+---
+title: Apologies for the duplicate RSS entries
+relativeUrl: /feed.xml
+tags: feed
+---
+
+If you're an existing subscriber, you may have noticed that all of the feed items have resurfaced in your feed reader as new. This is because I discovered the data I was using as each feed item's guid, the field used by readers to determine if an entry was unique, was not sufficient. This caused a couple of my recent entries not to be surfaced by readers.
+
+The fix required changing the formulation of the guid, which will then cause RSS readers to believe every entry is new again. Sorry for the inconvenience, but it had to be done to ensure all future entries are surfaced. Fortunately, there aren't that many items on this feed.
+
+Hope you enjoy the new stuff! 🤘