[Docs] Quickstart notebook missing explanation of spectrum types (normal, virtual, formal integral) #3530
Description
The quickstart notebook plots three spectrum types i.e., normal packets, virtual packets, and formal integral. However it does not explain what each one means. A new user seeing three overlapping lines has no context for finding the differences.
I'd like to add a brief markdown cell after the spectrum plot explaining:
Normal packets: photons that escape directly through the simulation
Virtual packets: used to reduce noise in the spectrum estimate
Formal integral: the most accurate spectrum, computed by integrating over the photosphere
This makes the quickstart more self-contained for new users and researchers exploring TARDIS for the first time.
GSoC 2026 applicant for the Automated Visualization Notebooks project.