[jdk17u-dev] RFR: 8357799: Improve instructions for JFileChooser/HTMLFileName.java

[Goetz Lindenmaier]

I backport this for parity with 17.0.18-oracle

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Commit messages:
 - Backport 53a83d15a1b5686ed0f2aeb3d30cd46b73f80733

Changes: https://git.openjdk.org/jdk17u-dev/pull/4030/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk17u-dev&pr=4030&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8357799
  Stats: 48 lines in 1 file changed: 19 ins; 10 del; 19 mod
  Patch: https://git.openjdk.org/jdk17u-dev/pull/4030.diff
  Fetch: git fetch https://git.openjdk.org/jdk17u-dev.git pull/4030/head:pull/4030

PR: https://git.openjdk.org/jdk17u-dev/pull/4030