Feature: Add signpath.io note & more docs

[BornToBeRoot]

Please provide some details about this pull request:

• Note to signpath on download, readme & blog page

ToDo:

• [x] Update documentation to reflect this changes
• [x] Update changelog to reflect this changes

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• [x] I have read and understood the contributing guidelines and the code of conduct.
• [x] I have have added my name, username or email to the contributors list or don't want to.
• [x] The code or resource is compatible with the GNU General Public License v3.0.