Document BIM working plane restore fix

[100more]

Document BIM working plane restore fix

Summary

• Add a FreeCAD 1.2 BIM release-note entry for BIM: restore working plane after recentering FreeCAD/FreeCAD#28836.
• Keep translation files untouched; the PR now only updates the source release-note page.
• Keep the change scoped to release notes; no command pages or generated content are edited.

Contributes to #26.
Contributes to #30.

Why this is low-risk

• Documentation-only change.
• Uses the same bullet and upstream pull-request link style already present in the file.
• Touches only wiki/Release_notes_1.2.wikitext after maintainer feedback.

Files changed

• wiki/Release_notes_1.2.wikitext - modified: Adds the BIM working-plane restore release-note bullet.

Coverage

• Checked this is not covered by an existing open documentation PR for PR #28836, recentering, or working-plane restore.

Verification

• git diff --check origin/main...HEAD - passed

Reviewer notes

• I removed the wiki/en/Release_notes_1.2.wikitext change in response to the translation-file guidance.

Boundary note

No payment, account, secret, or private contact details are included in this PR.

[Reqrefusion]

"en" files should not be modified. All translation files should remain untouched.

[100more]

Thanks for the review. I updated the branch so translation files are untouched now:

• removed the wiki/en/Release_notes_1.2.wikitext change from the PR diff
• kept the release-note entry only in wiki/Release_notes_1.2.wikitext
• re-ran git diff --check origin/main...HEAD

Happy to adjust anything else that would make this easier to merge.