docs(discussions): add lightweight q-and-a discussion template (#5385)

Problem
- The previous discussion-template proposal in #4902 used an invalid
GitHub Discussions form schema, so it could not be used as-is.
- Based on review feedback, the discussion template should be much
lighter-weight and focused on Q&A only.

Change
- add a single lightweight Q&A discussion form at
`.github/DISCUSSION_TEMPLATE/q-a.yml`
- make most technical fields optional and explicitly ask users to fill
them only when relevant
- align field names with the existing issue templates where practical
- document the discussion-template slug/schema constraints in
`.github/DISCUSSION_TEMPLATE/README.md`
- keep the documentation changes that were already part of #4902

Notes
- This PR supersedes #4902.
- The discussion form filename now matches the category slug
(`q-a.yml`), and the top-level schema uses supported keys only.

Authored by OpenClaw (model: gpt-5.4)


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Documentation**
* Added a new Q&A discussion template for GitHub Discussions with
structured form fields to capture technical questions, environment
details, versions, and reproducible examples.
* Added documentation describing available discussion templates and
usage guidelines for community contributions.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: njzjz <9496702+njzjz@users.noreply.github.com>

Author: 4 people

.github/DISCUSSION_TEMPLATE/README.md

@@ -0,0 +1,13 @@
+# Discussion Templates
+
+This directory contains GitHub Discussion category forms for DeePMD-kit.
+
+## Active template
+
+- `q-a.yml` → **Q&A**
+
+## Notes
+
+- The filename must match the discussion category slug exactly.
+- GitHub Discussion forms only support a limited set of top-level keys, such as `title`, `labels`, and `body`.
+- This Q&A template is intentionally lightweight; most fields are optional and should be filled only when relevant.

.github/DISCUSSION_TEMPLATE/q-a.yml

@@ -0,0 +1,92 @@
+title: "[Q&A] "
+labels: ["question"]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Use this form for Q&A discussions.
+
+        This template is intentionally lightweight.
+        **Only fill the technical fields below if they are relevant to your question.**
+
+        If your question is about using DeePMD-kit or diagnosing a problem, version info and a minimal reproducible example can help others answer faster.
+  - type: textarea
+    id: question
+    attributes:
+      label: Question
+      description: Please describe your question clearly.
+      placeholder: What would you like to ask?
+      value:
+    validations:
+      required: true
+  - type: input
+    id: version
+    attributes:
+      label: DeePMD-kit Version
+      description: "If applicable: `dp --version`."
+      placeholder: "e.g., 2.2.7"
+    validations:
+      required: false
+  - type: input
+    id: backend-version
+    attributes:
+      label: Backend and its version
+      description: "If applicable: the backend and its version will be printed when running DeePMD-kit, e.g. TensorFlow v2.15.0."
+      placeholder: "e.g., TensorFlow v2.15.0"
+    validations:
+      required: false
+  - type: textarea
+    id: other-version
+    attributes:
+      label: Python Version, CUDA Version, GCC Version, LAMMPS Version, etc
+      description: "If applicable, specify your platform or environment details."
+      placeholder:
+      value:
+    validations:
+      required: false
+  - type: textarea
+    id: details
+    attributes:
+      label: Details
+      description: "If applicable, add more context such as what you are trying to do, what you have tried, and where you got stuck."
+      placeholder:
+      value:
+    validations:
+      required: false
+  - type: textarea
+    id: reproducible-example
+    attributes:
+      label: Reproducible Example, Input Files, and Commands
+      description: |
+        If applicable, provide a minimal reproducible example.
+        For software-usage questions, this is often the fastest way to get a useful answer.
+      placeholder: |
+        Commands:
+        ```bash
+        dp train input.json
+        ```
+
+        Input / config:
+        ```json
+        {
+          "model": {}
+        }
+        ```
+
+        Expected behavior:
+        ...
+
+        Actual behavior / error message:
+        ...
+      value:
+    validations:
+      required: false
+  - type: textarea
+    id: further
+    attributes:
+      label: Further Information, Files, and Links
+      description: Put any additional information here, including links to docs, papers, related issues, screenshots, or external resources.
+      placeholder:
+      value:
+    validations:
+      required: false