Indentation size for plain text files?

[0x5374656c6c6172]

Tried adding this to languages.toml with no effect:

[[language]]
name = "text"
scope = "source.text" # "text.text", "source.plain", etc
file-types = ["text"] # :echo %{language} -> text
indent = { tab-width = 2, unit = "  " }