Add a guide on how to transition from Metropolis

[jolars]

It would likely help existing users of Metropolis if we provided a document on how to transition from Metropolis to Moloch.

[samcarter]

Just jotting down notes from updating answers:

• replace \metroset{...} ⇒ \molochset{...}
• for users of the pgfplots theme: load them separately \usepackage{pgfplots,pgfplotsthemetol}
• Fonts: this replicates the font settings fairly well \usepackage[medium,light]{FiraSans} \usepackage[weight=Light,usefilenames]{firamath-otf} (but needs manual installation of font weights from https://github.com/firamath/firamath?tab=readme-ov-file#on-your-system )