Update issue templates

Adding design template

.github/ISSUE_TEMPLATE/design-requirement.md

+---
+name: Design requirement
+about: A ticket template for detailing software requirements and design tasks
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+## Description
+As an Author I want... so that I ...
+
+## Tasks
+- [ ] Gather, agree and link relevant user stories
+- [ ] Create initial design proposal
+- [ ] Hold design review with relevant stakeholders
+- [ ] Usability test design (if needed)
+- [ ] Design approved by relevant stakeholders
+- [ ] Break designs down into development backlog items
+
+## User stories
+- As an author, I want... so that I...
+
+## Linked requirements
+- linked item
+
+## DoD
+- [ ] An approved design solution translated into backlog items for development