Why not include the setup() invocation inside plugin/colorizer.vim?

[kutsan]

Is there any reason why not just simply add the line below inside plugin/colorizer.vim than telling people they should invoke setup() function after it's loaded?

lua require'colorizer'.setup()

Configuration options can be set by another config function as well.

[zeertzjq]

:ColorizerToggle seems to work even without calling setup(), and setup() can fail when termguicolors is false.