docs: edit link takes to 404

[THOUSAND-SKY]

The "edit" button on the top right leads to 404's, like https://github.com/nix-community/dream2nix/edit/main/modules/dream2nix/src/intro.md

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I discovered that, trying to edit a broken link on this:

See htop module definition here.

And that link should probably lead to https://github.com/nix-community/dream2nix/blob/main/examples/packages/basics/htop-with-flags/default.nix instead.