variants/thinknode_m5/platformio.ini contained actual WiFi SSID and
password credentials (Livebox-633C) committed by mistake. Replaced
with placeholder values consistent with other variants (myssid/mypwd).
Repeater and Room Server environments in variants/thinknode_m5/platformio.ini
were using 'Thinknode M2' as the ADVERT_NAME, causing M5 nodes to advertise
with the wrong device name on the mesh.
- env:ThinkNode_M5_Repeater: 'Thinknode M2 Repeater' -> 'Thinknode M5 Repeater'
- env:ThinkNode_M5_room_server: 'Thinknode M2 Room Server' -> 'Thinknode M5 Room Server'
