Fix helium material wording in pin-cell notebooks

[Sardor-tracker]

Description

The Goal 2 task list says to create a helium cell, although the gas-gap cell already exists. Change “helium cell” to “helium material” in both the exercise and answer notebooks so the task agrees with the later material creation and assignment.

Fixes #1013

Validation

• Both updated notebooks parse as valid JSON.
• Compared the saved branch files with the originals: exactly one Markdown line changes in each notebook.
• Code cells, outputs, metadata, and notebook structure are unchanged.
• Notebooks were not executed; this change only corrects instructional text.

General Checklist

• I have performed a self-review of the changes.
• The change is limited to the wording described in the issue.
• Black formatting — not applicable; no Python code changed.
• New tests — not applicable; documentation wording only.

LLM Disclosure

Sardor is a human contributor. Codex assisted with a two-word documentation correction and the PR description; no executable code was generated.

Were any large language models used to generate this change?

• Yes — OpenAI Codex
• No

Documentation Checklist

No classes, functions, interfaces, infrastructure, or behavior were added or changed. The affected tutorial instructions are updated in both notebook versions.

---

📚 Documentation preview 📚: https://montepy--1014.org.readthedocs.build/en/1014/

[MicahGale]

Which specific model did you use in Codex?

[MicahGale]

LGTM. Nice simple update.

[Sardor-tracker]

Which specific model did you use in Codex?

gpt-6.1-sol

[Sardor-tracker]

Thanks, Micah! Really appreciate you taking the time to review it. ср, 7 окт. 2026 г. в 20:05, Micah Gale ***@***.***>:

…

***@***.**** approved this pull request. LGTM. Nice simple update. — Reply to this email directly, view it on GitHub <#1014?email_source=notifications&email_token=CP4WV6643VRTAJJOBWYIRST5SZLSBA5CNFSNUABKM5UWIORPF5TWS5BNNB2WEL2QOVWGYUTFOF2WK43UKJSXM2LFO4XTKNBUGQYTIOJUGU22M4TFMFZW63VGMF2XI2DPOKSWK5TFNZ2KYZTPN52GK4S7MNWGSY3L#pullrequestreview-5444149455>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/CP4WV62FCSB5CFYGQB4HSX35SZLSBAVCNFSNUABFKJSXA33TNF2G64TZHM3TIMJSGEYTGMBYHNEXG43VMU5TKNZTHEZTCNJTGA2KC5QC> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/CP4WV6YSLMMGSWPHYSGCOOL5SZLSBA5CNFSNUABKM5UWIORPF5TWS5BNNB2WEL2QOVWGYUTFOF2WK43UKJSXM2LFO4XTKNBUGQYTIOJUGU22M4TFMFZW63VGMF2XI2DPOKSWK5TFNZ2KUZTPN52GK4S7NFXXG> and Android <https://github.com/notifications/mobile/android/CP4WV67S7YIFEWSUNZXHZUD5SZLSBA5CNFSNUABKM5UWIORPF5TWS5BNNB2WEL2QOVWGYUTFOF2WK43UKJSXM2LFO4XTKNBUGQYTIOJUGU22M4TFMFZW63VGMF2XI2DPOKSWK5TFNZ2K4ZTPN52GK4S7MFXGI4TPNFSA>. Download it today! You are receiving this because you authored the thread.Message ID: <idaholab/MontePy/pull/1014/review/5444149455 ***@***.*** com>