card actions- add center alignment in card.d.ts

[chakrachi]

please allow for center keyword in alignment for card actions

export declare class MatCardActions {
/** Position of the actions inside the card. */
align: 'start' | 'end' | 'center';
}

it works fine when added

[Splaktar]

Please submit Angular Material and CDK questions here and issues here. This repo is for AngularJS Material.

Thank you for taking the time to submit this issue. However it does not follow our required issue template.

Please file a new issue that follows the template. This gives the team the information needed to investigate the bug or prioritize the enhancement.