Update gh-aw install step to current version example

[Copilot]

The workshop install step showed an outdated gh-aw version example, which can mislead learners when their installed version is newer. This updates the example to match the latest referenced release and clarifies expected version drift.

• Install output example refresh

  • Updated workshop/06-install-gh-aw.md from:
    • gh-aw version 0.81.6
  • To:
    • gh-aw version 0.84.3 with guidance that the learner’s version may be higher.

• Learner expectation clarity

  • Added explicit wording to prevent false alarms when installed output exceeds the example version.

You should see output like `gh-aw version 0.84.3` (your version may be higher).

• Fixes [workshop-sync] workshop/06-install-gh-aw.md: outdated version example in install step #2487