Draft: [WIP] editorial updates to EarthObservation attitude tutorial

This provides editorial cleanup of the EarthObservation attitude tutorial.

I am flagging this as WIP because there are two parts that I'd like to clean up, but would like confirmation on:

• https://gitlab.orekit.org/orekit/orekit-tutorials/-/blob/develop/src/main/java/org/orekit/tutorials/attitude/EarthObservation.java#L99-101 uses "law", which implies some kind of legal rule or always valid method (e.g. "Moore's law"). It looks like the example is actually switching from a daytime / operational mode to a nighttime / standby mode. Is that the intent?
• https://gitlab.orekit.org/orekit/orekit-tutorials/-/blob/develop/src/main/java/org/orekit/tutorials/attitude/EarthObservation.java#L153-154 describes the switching logic in terms of "limb" which doesn't make sense to me. Is there another way to describe it? Would it be valid to say "shadow" or something like that?