chore(sites): add Dale Blackburn portfolio (gatsbyjs#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 gatsbyjs#1234, Addresses gatsbyjs#1234, Related to gatsbyjs#1234, etc.
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yarn.lock

@@ -9263,13 +9263,20 @@ rgba-regex@^1.0.0:
   resolved "https://registry.yarnpkg.com/rgba-regex/-/rgba-regex-1.0.0.tgz#43374e2e2ca0968b0ef1523460b7d730ff22eeb3"
   integrity sha1-QzdOLiyglosO8VI0YLfXMP8i7rM=
 
-rimraf@^2.2.8, rimraf@^2.5.0, rimraf@^2.5.4, rimraf@^2.6.1, rimraf@^2.6.2, rimraf@~2.6.2:
+rimraf@^2.2.8, rimraf@^2.5.0, rimraf@^2.5.4, rimraf@^2.6.2, rimraf@~2.6.2:
   version "2.6.3"
   resolved "https://registry.yarnpkg.com/rimraf/-/rimraf-2.6.3.tgz#b2d104fe0d8fb27cf9e0a1cda8262dd3833c6cab"
   integrity sha512-mwqeW5XsA2qAejG46gYdENaxXjx9onRNCfn7L0duuP4hCuTIi/QO7PDK07KJfp1d+izWPrzEJDcSqBa0OZQriA==
   dependencies:
     glob "^7.1.3"
 
+rimraf@^2.6.1:
+  version "2.6.2"
+  resolved "https://registry.yarnpkg.com/rimraf/-/rimraf-2.6.2.tgz#2ed8150d24a16ea8651e6d6ef0f47c4158ce7a36"
+  integrity sha512-lreewLK/BlghmxtfH36YYVg1i8IAce4TI7oao75I1g245+6BctqTVQiBP3YUJ9C6DQOXJmkYR9X9fCLtCOJc5w==
+  dependencies:
+    glob "^7.0.5"
+
 ripemd160@^2.0.0, ripemd160@^2.0.1:
   version "2.0.2"
   resolved "https://registry.yarnpkg.com/ripemd160/-/ripemd160-2.0.2.tgz#a1c1a6f624751577ba5d07914cbc92850585890c"