Add CITZ IMB Playbook to Resources page

[mark-a-wilson]

Acceptance Criteria

• [ ] Create a card and place it the column to the right of the "For Designers" links.
• [ ] cardTitle: "Modern Application Playbook"
• [ ] cardDescription: "This playbook is designed to help you on your IT project journey, and to navigate the development and support of government applications within an Agile framework. It provides you with a collection of references, tools, and best practices."
• [ ] externalLink: "Read the playbook" LINK: https://bcgov.github.io/CITZ-IMB-playbook/)

[mark-a-wilson]

Closing this issue as requirements have changed -- folded into #873