The config section of the manpage starts with:

There are several ways to turn the various knobs on `@TRANSFORMED_PACKAGE_NAME@`. In order of
ascending precedence, they are:

* `VARIABLE=foo @TRANSFORMED_PACKAGE_NAME@`
* </etc/vcsh/config>
* <$XDG_CONFIG_HOME/vcsh/config>
* `@TRANSFORMED_PACKAGE_NAME@ -c <file>`

But there is no mention of config.d. The README documentation mentions a config.d, but it's always in the context of mr. I don't dare to submit a pull request, given that I don't see in which order the config.d should be inserted.

Cheers, and thanks for the project. :)