Update issue templates

Author: garyb

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,10 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+

.github/ISSUE_TEMPLATE/feature-request.md

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+---
+name: Feature request
+about: Suggest types, functions, properties that may be missing
+title: ''
+labels: enhancement
+assignees: ''
+
+---
+
+### Prerequisites
+
+- [ ] Before opening an issue, please check the DOM standard (https://dom.spec.whatwg.org/). If it doesn't appear in this spec, it may be present in the spec for one of the other `purescript-web` projects. Although MDN is a great resource, it is not a suitable reference for this project.
+
+### Description
+
+<!-- A summary of the thing to include, with a link to the relevant section of the spec -->