Evaluate the naming of `expected` and `actual`

[shrink]

The naming of these inputs makes sense for comparisons but for more complex assertions, or assertions where there is an implicit target, it doesn't make as much sense. For example, an assertion that checks for a status code needs to accept a status code input (e.g: 200) and a list of one or more URLs to test. An assertion that checks if a number is even knows what it's testing for -- it just needs a list of numbers to test.

Expected is... the (optional) value that the assertion is testing for
Actual is... the (optional) value(s) that the assertion is perform the test on

A comprehensive description of each input with examples might help avoid the need to rename the inputs, or perhaps aliases for the inputs could work (may be confusing, though).

• expected / actual
• target / input
• for / against
• values

assertion: npm://@assertions/is-even
each: true
values: |
  2
  4
  6
  8

assertion: npm://@assertions/status-code
each: true
expected: 200
actual: |
  https://www.example.com/200
  https://www.example.com/200
  https://www.example.com/404