Add icon for RTE Jours Signalés custom integration

[hiteule]

Proposed change

Add icon for the RTE Jours Signalés custom integration.
It allows to have direct access into Home Assistant from the RTE API about the "Jours Signalés" used by french electricity providers.

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/hiteule/rte-jours-signales

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])