RFR: Created README for the project

[Jesper Wilhelmsson]

A readme file that will serve as the GitHub front page for the project.

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Commit messages:
 - Created README for the project

Changes: https://git.openjdk.java.net/guide/pull/8/files
 Webrev: https://webrevs.openjdk.java.net/guide/8/webrev.00
  Stats: 38 lines in 1 file changed: 38 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/guide/pull/8.diff
  Fetch: git fetch https://git.openjdk.java.net/guide pull/8/head:pull/8

PR: https://git.openjdk.java.net/guide/pull/8