PREOPS-1206: new tutorial demonstrating variable star science

[MelissaGraham]

commit: MLG updates

The NB wasn't quite ready to merge to main/prod, made a few final fixes.

General updates:

• removed italics
• removed template text
• removed the flake8 etc.

Section 1

• wrote an introduction and removed the template text that was there
• moved the 1.2 heading to above where the parameters are being defined and removed template text

Section 2.1

• changed title from "Section Sub-sub-heading" to be "Define star coordinates"

Section 2.2

• detect_isPrimary is boolean; changed the ">0.5" to "=1".

Also the sections were a bit wonky, there were two Section 2 and Section 3 had the wrong indentation -- fixed.