Fix 404s found by the link checker

[SethTisue]

* At ./_site/records/2022-Q1-activity-report.html:194:
  External link https://docs.scala-lang.org/getting-started/index.html failed (status code 404)
* At ./_site/records/2022-Q2-activity-report.html:396:
  External link https://docs.scala-lang.org/getting-started/index.html failed (status code 404)
* At ./_site/records/2022-Q2-activity-report.html:398:
  External link https://docs.scala-lang.org/getting-started/index.html failed (status code 404)
* At ./_site/records/2022-Q2-activity-report.html:515:
  External link http://www.scalacon.org/ failed (status code 403)
* At ./_site/records/2022-Q3-activity-report.html:346:
  External link https://akmetiuk.com/posts/2022-02-19-launching-rockets.html failed (status code 404)
* At ./_site/records/2022-Q4-activity-report.html:367:
  External link https://akmetiuk.com/posts/2022-02-19-launching-rockets.html failed (status code 404)
* At ./_site/records/2023-Q1-activity-report.html:513:
  External link https://www.scala-lang.org/blog-detail/2023/02/28/acceptd-to-gsoc-2023.html failed (status code 404)