docs: add CONTRIBUTING guide with first contribution section

[olitreadwell]

• I have followed the Your First Code Contribution section of the Contributing guide (this PR adds the guide; the section is at CONTRIBUTING.md#your-first-code-contribution)

Upstream target

themesberg/flowbite-react — no issue; self-found gap. The PR template links to a CONTRIBUTING.md that does not exist.

What changed

Adds CONTRIBUTING.md mirroring the repo's own contributing guide, apps/web/content/docs/getting-started/contributing.mdx (based on contributing-gen, the same template family as spicetify/cli), which already includes the "Your First Code Contribution" section the PR template links to. The standalone file makes the template anchor resolve and stays consistent with the website page.

Why

The PR template's first checkbox links to https://github.com/themesberg/flowbite-react/blob/main/CONTRIBUTING.md#your-first-code-contribution, which 404s: the repo has no CONTRIBUTING.md (verified: no file on main or develop; root listing has only README.md and readme-images). The content already exists as a website page, so this PR surfaces it as the file the template expects.

How to verify

• After merge, https://github.com/olitreadwell/flowbite-react/blob/main/CONTRIBUTING.md#your-first-code-contribution resolves to the "Your First Code Contribution" section.
• curl -s -o /dev/null -w '%{http_code}' https://raw.githubusercontent.com/olitreadwell/flowbite-react/main/CONTRIBUTING.md returns 200.
• Every external link in the file returns 200 (checked with curl; the one dead link inherited from the website guide, github.com/GNOME/byzanz, is replaced with github.com/phw/peek).

Coverage

N/A — docs-only, no coverage tool applies.

Checks run locally

• Content mirrors the repo's own apps/web/content/docs/getting-started/contributing.mdx (same sections, same commands, same links), with the stale "app folder" path corrected to apps/web.
• Anchor verified: heading "Your First Code Contribution" generates #your-first-code-contribution, matching the template link.
• All external links checked: 200 (byzanz replaced with peek; flowbite-react.com docs links are the same ones the website guide uses).
• Tests / Lint / Typecheck / Build: N/A — no code changed.

Style / template compliance

Follows the repo's PR template (checkbox above) and Conventional Commits commit style (docs: ...). The guide is the repo's own contributing-gen-based content, not a new structure.

Confidence: HIGH

Docs-only addition; content sourced from the repo's own guide, every link verified. Only residual risk: maintainers may prefer to keep the guide website-only.

AI assistance

Drafted with AI assistance. The gap was found and verified against the current repo (template link 404s, no CONTRIBUTING.md exists), the content is copied from the repo's own contributing page, every link was checked, and the diff was reviewed line by line before opening.

Recommendation

Ready to send upstream as-is.

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PROMOTION NOTE (remove this section before/when opening against upstream):

gh pr create --repo themesberg/flowbite-react --base main --head olitreadwell:docs/add-contributing-guide-v3

Prerequisites: none. No CLA/DCO bot found in themesberg/flowbite-react; no signed-commit requirement found.