Document JSON paths more clearly #1638
Description
The docs for JSON paths for some cheat codes like vm.writeToml and vm.writeJson are not very clear. We should include some more information about how the JSON path is expected to be formed. For example, using "key.foo" will fail saying the path doesn't exist, because it silently gets changed to "$key.foo" - what the user should really do here is either ".key.foo" or "$.key.foo".
The JSON paths are from https://docs.rs/jsonpath_lib/latest/jsonpath_lib/