update Velbus documentation

[cereal2nd]

Proposed change

Update the velbus documentation, the reconfigure flow was not documented in the previous PR

#42522

Type of change

• Spelling, grammar or other readability improvements (current branch).
• Adjusted missing or incorrect information in the current documentation (current branch).
• Added documentation for a new integration I'm adding to Home Assistant (next branch).
  • I've opened up a PR to add logos and icons in Brands repository.
• Added documentation for a new feature I'm adding to Home Assistant (next branch).
• Removed stale or deprecated documentation.

Additional information

• Link to parent pull request in the codebase:
• Link to parent pull request in the Brands repository:
• This PR fixes or closes issue: fixes #

Checklist

• This PR uses the correct branch, based on one of the following:
  • I made a change to the existing documentation and used the current branch.
  • I made a change that is related to an upcoming version of Home Assistant and used the next branch.
• The documentation follows the Home Assistant documentation standards.

[netlify]

✅ Deploy Preview for home-assistant-docs ready!

Name	Link
🔨 Latest commit	ae9f27b
🔍 Latest deploy log	https://app.netlify.com/projects/home-assistant-docs/deploys/694a4f3125f48c00085e1b07
😎 Deploy Preview	https://deploy-preview-42686--home-assistant-docs.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[Copilot]

Pull request overview

This PR updates the Velbus integration documentation to add information about the reconfiguration flow, which was missing from a previous pull request (#42522).

• Adds a configuration_basic block documenting the VLP file parameter
• Documents the re-configuration process with step-by-step instructions
• Clarifies that bus scan is less reliable than using a VLP file