docs: add issue templates

.github/ISSUE_TEMPLATE/bug-report.yml

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+name: Bug Report
+description: If something isn't working as expected.
+labels:
+  - bug
+body:
+  - type: textarea
+    id: overview
+    attributes:
+      label: Overview
+    validations:
+      required: true
+  - type: textarea
+    id: how-to-reproduce
+    attributes:
+      label: How to reproduce
+      description: |
+        Please see [the guide](https://github.com/suzuki-shunsuke/oss-contribution-guide#write-good-how-to-reproduce) too.
+        devcontainer.json should be not partial but complete configuration.
+        Please remove unneeded configuration to reproduce the issue.
+      value: |
+        .devcontainer/devcontainer.json
+
+        ```json
+
+        ```
+
+        Other related code
+
+        ```
+
+        ```
+
+        Executed command and output
+
+        ```console
+        $ 
+        ```
+    validations:
+      required: true
+  - type: textarea
+    id: expected-behaviour
+    attributes:
+      label: Expected behaviour
+    validations:
+      required: true
+  - type: textarea
+    id: actual-behaviour
+    attributes:
+      label: Actual behaviour
+    validations:
+      required: true
+  - type: textarea
+    id: note
+    attributes:
+      label: Note
+      description: Additional information about the discussion.
+    validations:
+      required: false

.github/ISSUE_TEMPLATE/config.yml

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+blank_issues_enabled: false
+contact_links:
+  - name: Discussions
+    url: https://github.com/orgs/aquaproj/discussions
+    about: Please create a discussion instead of issue
+  - name: Slack
+    url: https://gophers.slack.com/archives/C04RALTG29K
+    about: Please ask questions freely
+  - name: Discord
+    url: https://discord.com/channels/1141777454164365382/1162444533959757955
+    about: Please ask questions freely

.github/ISSUE_TEMPLATE/feature-request.yml

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+name: Feature Request
+description: If you want to add a feature.
+labels:
+  - enhancement
+body:
+  - type: textarea
+    id: feature-overview
+    attributes:
+      label: Feature Overview
+    validations:
+      required: true
+  - type: textarea
+    id: why
+    attributes:
+      label: Why is the feature needed?
+      description: Please explain the problem you want to solve.
+    validations:
+      required: true
+
+  - type: textarea
+    id: workaround
+    attributes:
+      label: Workaround
+      description: |
+        If you have any workaround, please explain it and why the workaround isn't enough.
+
+  - type: textarea
+    id: example-code
+    attributes:
+      label: Example Code
+      description: |
+        Please explain the feature with code. For example, if you want a new option, please explain the usage of the option.
+      value: |
+        ```console
+        $ 
+        ```
+
+        Configuration
+
+        ```json
+
+        ```
+    validations:
+      required: false
+  - type: textarea
+    id: note
+    attributes:
+      label: Note
+    validations:
+      required: false

.github/ISSUE_TEMPLATE/general.yml

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+name: General
+description: Please use this template only when other templates don't meet your requirement
+body:
+  - type: textarea
+    id: free-text
+    attributes:
+      label: Free Text
+    validations:
+      required: true