RFR: Use https for all links

[Jesper Wilhelmsson]

Use https for all links

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Commit messages:
 - Use https for all links

Changes: https://git.openjdk.java.net/guide/pull/23/files
 Webrev: https://webrevs.openjdk.java.net/guide/23/webrev.00
  Stats: 55 lines in 8 files changed: 0 ins; 0 del; 55 mod
  Patch: https://git.openjdk.java.net/guide/pull/23.diff
  Fetch: git fetch https://git.openjdk.java.net/guide pull/23/head:pull/23

PR: https://git.openjdk.java.net/guide/pull/23