Documentation missing "option" in scope discussion

[kayavila]

The section under https://docs.zeek.org/en/master/scripting/basics.html#scope is a bit hard to understand. There's no discussion of variables declared with option, so for someone not very familiar with Zeek scripting, it's unclear how this relates to global or const. This is despite option being used in the example scripts above, and even (in the section explaining detect-MHR.zeek) referred to as constants.

Additional points that would be nice to have handled -

• Are const and option different?
• With const only redefinable before run-time, why would a script writer choose them rather than global? Is the sole purpose making sure they aren't altered again, or is there some memory benefit?
• An example using global would be helpful, especially showing how it differs from option.