Include directive in topgrade.toml

[openjck]

I want to suggest some general feature

I want to suggest that topgrade add an include directive in its configuration file, so that configuration can be included from another named file. This feature is supported by other tools, including Bash (source), tmux (source-file), Vim (source), OpenSSH (Include), Git ([include]) and others.

I find this ability helpful when I synchronize dotfiles between computers, but want one small piece of configuration to be different on a particular computer for some reason. For example, my Git configuration file (.config/git/config) uses my personal email address, but also includes this section at the bottom:

[include]
  # Include local configurations, if any.
  path = config.local

On my work computer, the config.local file sets the email address to my work email address.

With topgrade, I would do something similar, using this ability to run certain custom commands on some machines, but not others.

I would be happy to help test this.