chore(sites): add Dale Blackburn portfolio (#11564)

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## Description

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This PR adds my website to the showcase page.

## Related Issues

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  Link to the issue that is fixed by this PR (if there is one)
  e.g. Fixes #1234, Addresses #1234, Related to #1234, etc.
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docs/sites.yml

@@ -4169,3 +4169,14 @@
     - Nonprofit
     - Technology
   featured: false
+- title: Dale Blackburn - Portfolio
+  url: https://dakebl.co.uk/
+  main_url: https://dakebl.co.uk/
+  source_url: https://github.com/dakebl/dakebl.co.uk
+  description: >
+    Dale Blackburn's personal website and blog.
+  categories:
+    - Blog
+    - Portfolio
+    - Web Development
+  featured: false