RFR: 8336592: Wrong type in documentation for TreeTableView

[ANUPAM DEV]

Hello,

There is a typo in TreeTableView.java documentation. TreeTableColumns is used instead of TreeTableColumn.
I have updated the below lines:

TreeTableColumn<File, String> fileNameCol = new TreeTableColumn<>("Filename");
 TreeTableColumn<File, Long> sizeCol = new TreeTableColumn<>("Size");

Please review.

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Commit messages:
 - Update documentation for TreeTableView.java

Changes: https://git.openjdk.org/jfx/pull/1509/files
  Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1509&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336592
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jfx/pull/1509.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1509/head:pull/1509

PR: https://git.openjdk.org/jfx/pull/1509