[jfx11u] RFR: 8279396: Define version in .jcheck/conf

[Kevin Rushforth]

Backport fix to add `version` property to `.jcheck/conf`. This is needed in support of a Skara bot config change to take the fix version from the repo.

NOTE: the `UPDATING-version.md` file was not present in the repo. I copied it from mainline, since the instructions are identical.

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Commit messages:
 - 8279396: Define version in .jcheck/conf

Changes: https://git.openjdk.java.net/jfx11u/pull/68/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jfx11u&pr=68&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8279396
  Stats: 41 lines in 2 files changed: 41 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx11u/pull/68.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx11u pull/68/head:pull/68

PR: https://git.openjdk.java.net/jfx11u/pull/68