Installation instructions:

The plugin system on RED-DiscordBot works through user maintained repositories which can be enabled by adding them into the bot straight from the Discord server the bot is connected to. After a repository has been added, plugins ("Cogs") can be installed by referencing the repository and a cog within that repository.

Install repository:

[p]cog repo add BombiCogs https://github.com/WhiteBombi/BomboCogs

Output:

You're about to add a 3rd party repository. The creator of Red and its community
have no responsibility for any potential damage that the content of 3rd party
repositories might cause. By typing 'I agree' you declare to have read and
understand the above message. This message won't be shown again until the next reboot.

Agree you have read the message:

I agree

Output:

Repo 'BombiCogs' added.

Available cogs in a repository can be found with:

[p]cog list BombiCogs

Available cogs can be installed with:

[p]cog install BombiCogs countdown