Added script for i3status-rust

[totikom]

Added an example script for i3status-rust bar. It is largely based on script for waybar with following additions:

• added case charge when available
• block is shown only if buds are connected
• only connected buds battery level is shown (if only one of the buds is connected, you'll see that)
• color of the block is changed based on battery level: green for >50%, yellow for 30-49% and red for 0-29% (the minimum among two buds is used)

block config example:

[[block]]
block = "custom"
command = "/path/to/script.sh"
json = true
interval = 5 # seconds between updates
hide_when_empty = true # don't show this block then buds are not connected