docs: update frontend documentation to remove outdated init-frontend command

[omkute10]

Description

• Updated the frontend documentation to remove references to the non-existent init-frontend command
• Added clear instructions for accessing the frontend in modern versions of Augur
• Documented the default frontend ports (5000 and 5002) and their behavior
• Added a note about production deployment with nginx

This PR fixes #3377 by updating the outdated frontend setup documentation.

Notes for Reviewers

• The uv run augur config init-frontend command no longer exists in modern Augur versions
• The frontend is now automatically served when starting Augur with augur run
• The documentation now accurately reflects the current behavior

Signed commits

• [x] Yes, I signed my commits.

[MoralCode]

Also, you dont need to re-create PRs to update them, pushing to, or even force-pushing to the branch that you created the PR with will automatically update it