keyArgs is assumed to `false` when using both merge and read in typePolicies

I was using both merge and read on typePolicies, and found out that the read function didn’t have the correct cache key, hence returned the wrong result for the query.

And then I found this comment in the code (ref).

// If we have both a read and a merge function, assume
// keyArgs:false, because read and merge together can take
// responsibility for interpreting arguments in and out. This
// default assumption can always be overridden by specifying
// keyArgs explicitly in the FieldPolicy.

I wouldn’t have known that I need to specify keyArgs or the problem arose because I have both merge and read in the policy. I think it should be documented in this section.

Thanks for this suggestion @tuanalumi! Would you be willing to submit a pull request with a suggested change?