Add a note about boolean flags

[daedalus28]

We should a note like this:

In general, we prefer designing APIs such that boolean flags are opt in - so true changes the behavior. APIs that set boolean values to default to true are confusing in JS because it means that true and "missing" (or undefined) behave the same and only false is different.

We should generally strive to ensure that for boolean flags, omitting a flag and explicitly marking it as false behave the same way. Sometimes this means you just invert the name - for example, contexture-client has disableAutoUpdate as a flag which you can opt in to instead of autoUpdate which would have to default to true (and thereby make undefined and true behave the same)

Opened as an issue first in case anyone has any points to bring up