Add Homey integration to integrations docs

[rdmn7]

Hi evcc docs team,

I maintain a community Homey integration for evcc and would like to have it listed in the Integrations section if you think it fits.

Integration repository: https://github.com/rdmn7/com.evcc.io
GitHub handle: @rdmn7
Homey app id: com.evcc.io

The integration connects Homey to a local evcc instance for charging point control, site energy readings, and optional home battery monitoring/control. It is a community integration and is not an official evcc project.

Thanks!