docs: Clarify issues vs discussions

[alessfg]

Proposed changes

See title.

Checklist

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• I have read the contributing guidelines.
• I have signed the F5 Contributor License Agreement (CLA).
• If applicable, I have added tests that prove my fix is effective or that my feature works.
• If applicable, I have checked that any relevant tests pass after adding my changes.
• I have updated any relevant documentation (README.md and/or CHANGELOG.md).

[Copilot]

Pull Request Overview

This PR updates documentation to clarify the distinction between issues and discussions. It removes the mailing list section from SUPPORT.md and revises the community support instructions in the issue templates to direct users to the appropriate channels.

• Removed outdated mailing list information from SUPPORT.md.
• Updated wording in feature request and bug report templates to better differentiate between community support channels.
• Adjusted repository link placeholders in the issue templates.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
SUPPORT.md	Removed mailing list section for clarity.
.github/ISSUE_TEMPLATE/feature_request.yml	Revised note to guide users to the correct support channel and updated link placeholders.
.github/ISSUE_TEMPLATE/bug_report.yml	Revised note to guide users to the correct support channel and updated link placeholders.

Comments suppressed due to low confidence (2)

.github/ISSUE_TEMPLATE/feature_request.yml:15

• [nitpick] Verify that the placeholders '{{REPOSITORY_OWNER}}' and '{{REPOSITORY_URL}}' correctly resolve to the intended repository information. Consider using a more standard variable name if available.

[issue search]: https://github.com/{{REPOSITORY_OWNER}}/{{REPOSITORY_URL}}/search?q=is%3Aissue&type=issues

.github/ISSUE_TEMPLATE/bug_report.yml:17

• [nitpick] Verify that the placeholders '{{REPOSITORY_OWNER}}' and '{{REPOSITORY_URL}}' correctly resolve to the intended repository information. Consider using uniform variable names across templates if needed.

[issue search]: https://github.com/{{REPOSITORY_OWNER}}/{{REPOSITORY_URL}}/search?q=is%3Aissue&type=issues