documenting reserved words

I just reviewed #61 and ended up with some questions.

I think this might be good to document a bit on the main readme docs. What happens when I use a reserved word in my log statements? prefix disappears weirdly, but lvl just shows up and doesn't change the lvl? I could maybe make a table but I don't know well enough I don't remember exactly how each of them is used.

I'm also curious why are there reserved words in the log line stuff? what does that help with, like these aren't for the logger options these are on each log line so I'm just confused how they work? do some of them get used?

Start by reviewing issue #61 and the main README documentation. Investigate how reserved words behave in log statements, including the reported prefix and lvl behavior, and why they exist in log lines. Done means the README clearly explains the reserved words, their effects, and their purpose.

Written by the indexing model from the issue text.