8376836: Fix mistakes in FX API docs

[nlisker]

Fixes the typos listed in the JBS issue.

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Progress

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Issue

• JDK-8376836: Fix mistakes in FX API docs (Bug - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jfx.git pull/2239/head:pull/2239
$ git checkout pull/2239

Update a local copy of the PR:
$ git checkout pull/2239
$ git pull https://git.openjdk.org/jfx.git pull/2239/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 2239

View PR using the GUI difftool:
$ git pr show -t 2239

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jfx/pull/2239.diff

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[openjdk]

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See the Progress checklist in the description for automated requirements.