#53 Small Typos in Python Module obsterms Documentation

[Jared Bland]

There's a small typo in the first section, https://openmps.sourceforge.io/pyautodoc/obsterms.html#defining-observables, where is looks like there was a LaTeX typo under the 'corr' observable - it's understandable as is, but just pointing it out.

Slightly more important is that there does seem to be a small typo in the manual wherein it says to use AddObservables(quantum information quantity of interest): https://openmps.sourceforge.io/mps_chapters/simulationdetails.html?highlight=densitymatrix_i#defining-observables
I get an error with AddObservables as opposed to AddObservable. Not a big deal, but it would be good to have clear.

Thanks for everything!
Jared