[Documentation] Describe `log!` usage and link to it in `error!`

[Ben-PH]

See #506

Currently, the output of log! is not Just Right™ due to manner in which Rust and JS interact (to my understanding). Though things are in a good place and usable, Rusty habits and assumptions about how to format for console, and what the output will look like exactly, can mislead the unaware log! user.

Getting it "Just Right" is likely out of scope. Outlining this in documentation should equip the user to be aware of the little quirks and plan accordingly.

Expect a PR on this from me later today.