Docs: restore local dev port to 9001
Since the migration to Astro, the localhost port is now 4321. This PR updates the README's "Running documentation locally" to reflect this change.
Thanks, but the fix should be restoring the port back to 9001 :). Feel free to update here if you want, otherwise I'll swing back to this.
Done: restored port 9001 in the docs-serve NPM script, as it was prior to #41251. Also reverted the port number in contribute.mdx page.
Thanks @julien-deramond. Great job on the Astro port! It made me want to explore the tool more.
Btw, I just rebased and pushed a tweak to the contribute page (3905606) so that it matches the README URL and is also clickable. Hopefully that works for you: https://deploy-preview-41545--twbs-bootstrap.netlify.app/docs/5.3/getting-started/contribute/#local-documentation