DOC: dev guide: mention the executable
DOC: dev guide: mention the executable

fixes certtools/intelmq#803

Signed-off-by: Sebastian Wagner <1b00c120e1c33c7e19a7cb69011b74f705830cf8@sebix.at>

certtools/intelmq,aaronkaplan/intelmq,certtools/intelmq,aaronkaplan/intelmq,certtools/intelmq,aaronkaplan/intelmq