Add structured issue templates for bugs, enhancements, and documentation

[fellyph]

Motivation for the change, related issues

This pull request introduces a set of structured, YAML-based issue templates to improve the quality and consistency of issue reporting in the repository. By guiding contributors to provide specific and relevant information, these templates will help maintainers triage, understand, and resolve issues more efficiently.

This new system replaces the free-form issue creation process with three dedicated workflows:

1. Bug Report: For reporting reproducible software defects.
2. Enhancement Request: For proposing new features or improvements to existing functionality.
3. Documentation Improvement: For suggesting corrections, updates, or additions to the project's documentation.

Changes Included

This PR adds the following three new files to the .github/ISSUE_TEMPLATE/ directory:

1. 1-bug-report.yml

   • Creates a detailed form for submitting bug reports.
   • Includes fields for prerequisites, a bug summary, expected vs. actual behavior, steps to reproduce, and problem isolation checklists.
   • Automatically applies the [Type] Bug label to new issues.

2. 2-enhancement.yml

   • Provides a template for feature and enhancement requests.
   • Prompts the user to describe the desired solution, considered alternatives, and any additional context.
   • Automatically applies the [Type] Enhancement label to new issues.

3. 3-documentation-improvement.yml

   • Offers a structured way to suggest documentation changes.
   • Includes fields for describing the request, the reason for it, links to relevant pages, and potential content.
   • Automatically applies the [Type] Documentation label and adds a cc @fellyph to the issue body for notification.

[adamziel]

Let's still have a freeform template in addition to those options – sometimes that's all you need. E.g. Woo has this option:

[fellyph]

@adamziel, I have enabled the Blank issue

[adamziel]

Nice! Good work @fellyph ❤️