RFR: 8232522: FX: Update copyright year in docs, readme files to 2020

[Kevin Rushforth]

As indicated in the JBS bug, this makes the needed change for releasing in 2020.

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Commits:
 - 85c03ad9: 8232522: FX: Update copyright year in docs, readme files to 2020

Changes: https://git.openjdk.java.net/jfx/pull/18/files
 Webrev: https://webrevs.openjdk.java.net/jfx/18/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8232522
  Stats: 3 lines in 3 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.java.net/jfx/pull/18.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/18/head:pull/18

PR: https://git.openjdk.java.net/jfx/pull/18