docs: improve assert docs
This improves the error example output by reflecting the current
state. It also makes sure the examples are up to date in general.
assert.throws
clarified the ERR_AMBIGUOUS_ARGUMENT
error.
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
documentation is changed or added -
commit message follows commit guidelines