RFR: 7903962: Update IDEA plugin documentation

Fri Mar 7 14:39:55 UTC 2025

Update menu item location to open default settings window.

Current location is: `File -> New Projects Setup -> Settings for New Projects...`

Checked in "IntelliJ IDEA 2024.3.2.2 (Community Edition)".

![Default settings menu location](https://github.com/user-attachments/assets/e9b94e74-5bea-476f-bcb1-f75ce76f3fc2)

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Commit messages:
 - Update README.md

Changes: https://git.openjdk.org/jtreg/pull/247/files
  Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=247&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903962
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jtreg/pull/247.diff
  Fetch: git fetch https://git.openjdk.org/jtreg.git pull/247/head:pull/247

PR: https://git.openjdk.org/jtreg/pull/247