RFR: Remove unused files

[Magnus Ihse Bursie]

Jesper asked me to remove those files :). If I do this before splitting index.md, that patch gets easier.

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Commit messages:
 - Remove unused files.

Changes: https://git.openjdk.java.net/guide/pull/83/files
 Webrev: https://webrevs.openjdk.java.net/?repo=guide&pr=83&range=00
  Stats: 187 lines in 4 files changed: 0 ins; 187 del; 0 mod
  Patch: https://git.openjdk.java.net/guide/pull/83.diff
  Fetch: git fetch https://git.openjdk.java.net/guide pull/83/head:pull/83

PR: https://git.openjdk.java.net/guide/pull/83