Added configuration info the Lanbon L8-HD dimmer

[janick]

Brief description of the changes

Documentation that goes with esphome/esphome#8255

Type of changes

• [ ] New device
• [X] Update existing device
• [ ] Removing a device
• [ ] General cleanup
• [ ] Other

Checklist:

• [X] There are no passwords or secrets references in any examples. The only exceptions are !secret wifi_ssid and !secret wifi_password.
• [X] The wifi or ethernet block has no static / manual ip address specified.
• [X] The first configuration provided should be hardware definitions only. A more involved example can be provided in a separate configuration block.

[netlify[bot]]

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