Checker description

[Xyene]

Would be nice to have a reference of what builtin checker does what. A table like

Checker ID	Extra parameters	Description
standard	—	describe whitespace-ignoring behaviour
floats	precision (float)	describe abs/rel precision

For all checkers in https://github.com/DMOJ/judge/tree/master/dmoj/checkers

[int-y1]

Checkers are in docs/problem_format/custom_checkers.md.

Remaining checkers: linematches, rstripped