Add icons/logo for gtfs_realtime custom integration

[bcpearce]

Proposed change

Adds icons for GTFS Realtime custom integration.

Type of change

• Add a new logo or icon for a new core integration
• Add a missing icon or logo for an existing core integration
• Add a new logo or icon for a custom integration (custom component)
  • I've added a link to my custom integration repository in the PR description
  • I've opened up a PR for my custom integration on the Home Assistant
    Python wheels repository
• Replace an existing icon or logo with a higher quality version
• Replace an existing icon or logo after a branding change
• Removing an icon or logo

Additional information

• This PR fixes or closes issue: fixes #
• Link to code base pull request:
• Link to documentation pull request:
• Link to integration documentation on our website:
• Link to custom integration repository: https://github.com/bcpearce/homeassistant-gtfs-realtime

Checklist

• The added/replaced image(s) are PNG
• Icon image size is 256x256px (icon.png)
• hDPI icon image size is 512x512px for ([email protected])
• Logo image size has min 128px, but max 256px, on the shortest side (logo.png)
• hDPI logo image size has min 256px, but max 512px, on the shortest side ([email protected])

• only icon is added, it doubles as the logo

[frenck]

Thanks, @bcpearce 👍

../Frenck