isTypeOf config parameter missing from StrongObjectTypeConfig type

[karoun]

The isTypeOf option is mentioned in the README, but isn't implemented in source:

graphql-strong/README.md

Lines 187 to 189 in c85a0c7

	- `name: string`: The required name of your type.
	- `description?: string`: An optional description of your type.
	- `isTypeOf: (value: any, context: TContext) => value is TValue`: A function you define which will verify if a value is indeed of the type you created.

graphql-strong/src/object.ts

Lines 19 to 26 in c85a0c7

	/**
	* A configuration object to be used when creating object types. Any extra
	* options will go straight into the type config.
	*/
	export type StrongObjectTypeConfig<TValue, TContext> = {
	readonly name: string,
	readonly description?: string | undefined,
	};

It should be added to the StrongObjectTypeConfig type as an optional parameter.