[Auto Discovery] Add support for light_klx

[rschuiling]

For the Bresser 7 in 1 weather station most values are included, except for this one:
Skipped Bresser-7in1/xxxxx: light_klx

Can light_klx be added to the list of supported keys? I think it's suppossed to report kilo lux.

[deviantintegral]

Hi, the discovery script is part of rtl_433 itself, so please file an issue there: https://github.com/merbanan/rtl_433/issues

If you or someone else adds support in a pull request, I will be happy to patch it in here once it's available.

[catduckgnaf]

If you don't want to wait for upstream! check out
https://github.com/catduckgnaf/rtl_433_ha