Update Remix instructions to a working version

[Hansenq]

Changes

Updates the Posthog Remix guide to a version that correctly sets up Posthog in Remix. These instructions were determined by me through setting up my own Remix app, referencing the existing guide, referencing the React guide, referencing this guide that's also incorrect, and referencing this issue that I ran into only when deploying to prod.

Checklist

• Words are spelled using American English
• Titles are in sentence case
• Feature names are in sentence case too
• Use relative URLs for internal links
• If I moved a page, I added a redirect in vercel.json
• Remove this template if you're not going to fill it out!

Article checklist

• I've added (at least) 3-5 internal links to this new article
• I've added keywords for this page to the rank tracker in Ahrefs
• I've checked the preview build of the article
• The date on the article is today's date
• I've added this to the relevant "Tutorials and guides" docs page (if applicable)

Useful resources

• The PostHog style guide
• Full list of tags and categories
• List of content components
• PostHog SEO best practices

[vercel]

@Hansenq is attempting to deploy a commit to the PostHog Team on Vercel.

A member of the Team first needs to authorize it.