docs: upgrade issue templates to form format.

This closes #518.

Author: buehler

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,44 @@
+name: Bug Report
+description: "Create a report to help fix a problem."
+title: "[bug]: "
+labels: ["bug"]
+body:
+- type: markdown
+  attributes:
+    value: |
+      Thanks for taking the time to fill out this bug report!
+- type: textarea
+  id: description
+  attributes:
+    label: Describe the bug
+    description: A clear and concise description of what the bug is.
+  validations:
+    required: true
+- type: textarea
+  id: reproduce
+  attributes:
+    label: To reproduce
+    description: Steps to reproduce the behaviour
+    placeholder: |
+      Steps to reproduce the behavior:
+      1. Go to '...'
+      2. Click on '....'
+      3. Scroll down to '....'
+      4. See error
+  validations:
+    required: true
+- type: textarea
+  id: expected
+  attributes:
+    label: Expected behavior
+    description: A clear and concise description of what you expected to happen.
+- type: textarea
+  id: screenshots
+  attributes:
+    label: Screenshots
+    description: If applicable, add screenshots to help explain your problem.
+- type: textarea
+  id: additional
+  attributes:
+    label: Additional Context
+    description: Please add any other infos that could be useful.

.github/ISSUE_TEMPLATE/bug_report.yaml

@@ -0,0 +1,12 @@
+name: Documentation
+description: "Suggest a topic that is not correctly documented (or not documented at all)"
+title: "[docs]: "
+labels: ["documentation"]
+body:
+- type: textarea
+  id: description
+  attributes:
+    label: Describe the missing piece of documentation
+    description: Describe what you miss in the docs (or what is wrong).
+  validations:
+    required: true

.github/ISSUE_TEMPLATE/documentation.md

@@ -0,0 +1,26 @@
+name: Feature Request
+description: "Suggest a new feature for this project."
+title: "[feature]: "
+labels: ["enhancement"]
+body:
+- type: markdown
+  attributes:
+    value: |
+      Thanks for taking the time to fill out this feature request!
+- type: textarea
+  id: description
+  attributes:
+    label: Is your feature request related to a problem? Please describe.
+    description: A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+- type: textarea
+  id: solution
+  attributes:
+    label: Describe the solution you would like
+    description: A clear and concise description of what you want to happen.
+  validations:
+    required: true
+- type: textarea
+  id: additional
+  attributes:
+    label: Additional Context
+    description: Please add any other infos that could be useful.