update Buttons relays switches description

[ouinouin]

For the ESP_32 section, the relays switches buttons descritpion was incomplete, added descrption for _d (pulldown) _i (inverted active high) , _n (no pullup) taking reference the related esp8266 peripheral section when possible. did vertical bar separator cosmetic realignment on markdown source. (hence changed lines nr.)

[DeflateAwning]

@ouinouin, please look at the review suggestions and implement them!