Add template (#526)

.github/ISSUE_TEMPLATE/add_template.md

+---
+name: Add Template
+about: Request to add a template to Dyad Hub
+title: "Add Template: [Template Name]"
+labels: "add-template"
+assignees: ""
+---
+
+If you'd like to add a template to Dyad Hub, follow the [Add Template guide](https://dyad.sh/docs/templates/add-template).
+
+**Template name:**
+
+**Template description (1-2 sentences):**
+
+**GitHub repo:**
+
+**Screenshot**
+
+<!-- Please attach a screenshot of your template in action -->
+
+**Open Source License**
+
+- [ ] This template is open-source (e.g. MIT, Apache 2.0)