Review: pandas_panel.md

Part of #40 (Phase 1).

Native-speaker review of pandas_panel.md by @Honaminto.

How to reply. Open a PR editing the French directly — one PR for this lecture, titled e.g. [pandas_panel] Corrections — or leave line comments / suggestion blocks on it. Priorities: meaning errors, wrong technical terms, inconsistent terminology, unnatural French (academic register), anything in code comments that looks wrong. Ignore spacing before : ; ! ?, errors in the English, and the translation: header. A wrong term that recurs belongs on the terminology issue, not here.

Done when a PR by @Honaminto touching this file is merged, or he states here that the lecture needs no change. Either outcome is recorded; nothing is ticked by hand.

Apri lectures/pandas_panel.md nel repository francese e confrontalo con la fonte inglese collegata. Verifica il significato, i termini tecnici, la coerenza terminologica, il francese accademico e i commenti nel codice, rispettando le esclusioni indicate. Il lavoro è considerato concluso quando viene effettuato il merge di una PR di @Honaminto che modifica questo file, oppure quando conferma che non sono necessarie modifiche.