Add a sample post template

app/guide/a-sample-template.md

@@ -0,0 +1,48 @@
+---
+layout: page
+title: A post template
+description: Use this template to get you started.
+eleventyNavigation:
+  parent: Guide
+---
+
+Create a new subfolder for your post.
+
+Add an `index.md` file in the subfolder and copy in the markdown below.
+
+Delete the lines for any features you don’t need.
+
+```markdown
+---
+title: "Post title: try to keep it short!"
+date: 2025-12-01
+description: This description will appear on index pages.
+tags:
+  - add
+  - tags
+  - to help group
+  - related posts
+author:
+  - Your Name
+  - Another Name
+opengraphImage:
+  src: /your-service/2025/12/post-title/image-name.png
+  alt: Alternative text for the lead image (appears when sharing)
+---
+
+An intro paragraph which summarises the whole thing.
+
+## Heading
+
+Some content.
+
+[A link to another post](/your-service/2025/11/another-post-title/)
+
+### Subheading
+
+More content
+
+![Alt text for an image](/your-service/2025/12/post-title/image.jpg)
+
+
+```