Change from listening to watching in bot discord

[putrafirman]

maybe in next release, we can change this to watching or custom activity and binding to coingecko / binance url for see chart detail

const (
    ActivityTypeGame      ActivityType = 0
    ActivityTypeStreaming ActivityType = 1
    ActivityTypeListening ActivityType = 2
    ActivityTypeWatching  ActivityType = 3
    ActivityTypeCustom    ActivityType = 4
    ActivityTypeCompeting ActivityType = 5
)

[putrafirman]

will be implemented using method from discordgo. need to declare [UpdateStatusData]

func (*Session) [UpdateStatusComplex](https://github.com/bwmarrin/discordgo/blob/v0.25.0/wsapi.go#L385)

[putrafirman]

using activity type

ActivityTypeWatching  = 3