Local notebook configuration should be optional

[mickael-menu]

Only the presence of the .zk directory should be mandatory to mark a directory as a notebook.

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@mickael-menu quick question around global config/templates (https://github.com/mickael-menu/zk/blob/main/docs/config.md#global-configuration-file)..

there still seems to be a requirement that a config.toml exist in your notebook's directory (even the notebook defined in the ZK_NOTEBOOK_DIR; is this expected behaviour?

thanks!

Originally posted by @megalithic in https://github.com/mickael-menu/zk/issues/10#issuecomment-808359417