Use placeholder instead of value in issue templates

[senutpal]

Concisely describe the change

In .github/ISSUE_TEMPLATE/bug.yaml and .github/ISSUE_TEMPLATE/feature.yaml, default guidance text was set on attributes.value for textarea form fields. In GitHub Issue Forms, value pre-populates editable text inside input boxes, forcing users to manually highlight and delete default text whenever creating a bug report or feature proposal (Fixes #609).

Replaced attributes.value with attributes.placeholder across all textarea fields in bug.yaml and feature.yaml. placeholder provides a hint text inside empty text fields that automatically disappears upon typing without polluting submitted markdown or requiring manual deletion. Fixed minor typos (Consisely -> Concisely, folow -> follow, a LLM -> an LLM and removed copy-paste fragment in bug.yaml).

Before screenshot / screen recording

N/A (YAML issue form configuration change)

After screenshot / screen recording

N/A (YAML issue form configuration change)

Checklist

Ensure you have completed the following checklist for your pull request to be reviewed:

• Certify you wrote the patch or otherwise have the right to pass it on as an open-source patch by signing all
  commits. (git commit -s). (If needed, use git commit -s --amend). The author email must match
  the sign-off email address. See CONTRIBUTING.md
  for more information.
• Referenced issues using Fixes: #00000 in commit message (if applicable)
• PR description, commit message, and GitHub comments are human-written, per LLM Policy

[ashley-cui]

One small grammar nit. This is also kind of related, but could we use labels: ["bug"] instead of having Bug: in the title?

Thanks!

[ashley-cui]

Suggested change

	placeholder: Concisely describe the issue, and what page it is on. Do not use an LLM.
	placeholder: Concisely describe the issue, and what page it is on. Do not use a LLM.

[ashley-cui]

Suggested change

	placeholder: Concisely describe the feature. Do not use an LLM.
	placeholder: Concisely describe the feature. Do not use a LLM.

[senutpal]

@ashley-cui should I also update feature.yaml to labels: ["enhancement"] alongside bug.yaml or keep [Feature]: in the title ?
and also shouldn't it be an LLM ? since "LLM" is pronounced starting with a vowel sound.