[jfx17u] RFR: 8291630: Update attribution in webkit.md file

[Kevin Rushforth]

This is an effectively clean backport. The only difference is that one of the lines removed by the patch (removed both in jfx mainline and here) had been modified in jfx mainline to update the copyright year (modified incorrectly, as it turns out, but that's no longer relevant since the line has been removed).

The net result is that the `webkit.md` file is identical between mainline and jfx17u.

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Commit messages:
 - 8291630: Update attribution in webkit.md file

Changes: https://git.openjdk.org/jfx17u/pull/82/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx17u&pr=82&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8291630
  Stats: 1152 lines in 1 file changed: 931 ins; 189 del; 32 mod
  Patch: https://git.openjdk.org/jfx17u/pull/82.diff
  Fetch: git fetch https://git.openjdk.org/jfx17u pull/82/head:pull/82

PR: https://git.openjdk.org/jfx17u/pull/82