docs: clarify browser support and add issue severity classification

[rubencarvalho]

Description

This PR adds a new section to the CONTRIBUTING.md and README files to provide contributors with clear guidelines on the target browsers we support. It also adds a detailed defect severity classification table into the contribution guidelines and adds a "Issue Severity" dropdown field to the GitHub issues template.

Related issue(s)

• resolves Publicly document browser support policy. #3465
• SWC-52
• SWC-181

Motivation and context

We are aiming for greater transparency while at the same time formalizing some of our current practices and support mechanisms.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (minor updates related to the tooling or maintenance of the repository, does not impact compiled assets)

Checklist

• I have signed the Adobe Open Source CLA.
• My code follows the code style of this project.
• If my change required a change to the documentation, I have updated the documentation in this pull request.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• I have reviewed at the Accessibility Practices for this feature, see: Aria Practices

Best practices

This repository uses conventional commit syntax for each commit message; note that the GitHub UI does not use this by default so be cautious when accepting suggested changes. Avoid the "Update branch" button on the pull request and opt instead for rebasing your branch against main.

[github-actions]

Branch preview

• Documentation Site
• Storybook

[github-actions]

Tachometer results

Currently, no packages are changed by this PR...

[github-actions]

Lighthouse scores

Category	Latest (report)	Main (report)	Branch (report)
Performance	0.99	0.95	0.95
Accessibility	1	1	1
Best Practices	1	1	1
SEO	1	0.92	0.92
PWA	1	1	1

What is this?

Lighthouse scores comparing the documentation site built from the PR ("Branch") to that of the production documentation site ("Latest") and the build currently on main ("Main"). Higher scores are better, but note that the SEO scores on Netlify URLs are artifically constrained to 0.92.

Transfer Size

Category	Latest	Main	Branch
Total	222.409 kB	211.974 kB 🏆	212.028 kB
Scripts	55.031 kB	49.771 kB	49.686 kB 🏆
Stylesheet	34.493 kB	30.189 kB 🏆	30.332 kB
Document	6.043 kB	5.383 kB 🏆	5.387 kB
Font	126.842 kB	126.631 kB	126.623 kB 🏆

Request Count

Category	Latest	Main	Branch
Total	48	48	48
Scripts	40	40	40
Stylesheet	5	5	5
Document	1	1	1
Font	2	2	2

[najikahalsema]

Looking great so far. Since you're in here, could we also add some more specificity around using webcomponents.dev to provide your reproduction?

in bug_report.yaml:
line 65: "Sample code or abstract reproduction which illustrates the problem"

in contributing.md (it wouldn't let me comment on these lines for some reason)
lines 51-53
"Please reproduce your issue in an abstract environment, preferrably webcomponents.dev (use the existing link provided there). Screenshots or videos in your local dev environment are not sufficient enough to help us identify whether or not the issue originates from our library."

[najikahalsema]

Just one little thing. Otherwise, looks good! Thank you.

[najikahalsema]

Woohoo! Thank you!!!