docs: write upgrading guide

docs/guide/upgrading_v9/2563.md

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+### Expose signature parameters in `method` parameter of `faker.helpers.multiple`
+
+We now expose the parameters from the `method` parameter to our users.
+That allows for usecases where the index is part of the generated data e.g. as id.
+
+```ts
+faker.helpers.multiple((_, index) => ({ id: index, ...}), ...); // [{id: 0, ...}, ...]
+```
+
+While the actual implementation of the method hasn't changed, it's signature has.
+Previously it was possible to incorrectly pass any function reference to `faker.helpers.multiple`,
+even those that are incompatible with the actual parameters passed to the generator function.
+This change causes compile time errors only in cases that would otherwise be potential runtime errors.
+
+**Bad**
+
+```ts
+faker.helpers.multiple(faker.person.firstName, ...); // ❗
+// Argument of type '(sex?: "female" | "male" | undefined) => string'
+// is not assignable to parameter of type '(v: unknown, index: number) => unknown'.
+```
+
+**Good**
+
+```ts
+faker.helpers.multiple(() => faker.person.firstName(), ...); // ✔
+```