add digital-signage tag and three softwares

[sagiadinos]

Thanks for taking the time to suggest an addition to awesome-selfhosted!

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I created a new tag "digital-signage" and add three FOSS softwares.

[nodiscc]

Submit one item per pull request

[sagiadinos]

How should I handle the minimum 3 items requirement when introducing a new tag? The lint fails because no other items use this tag yet.