Problem: The key needs to be published in order for the signature-checker to work. Solution: Add a section about uploading the key to a server.
QubesOS/qubes-issues#3691
Removed some unnecessary parentheses around entire sentences and completely relevant clauses. Also expanded the Using PGP with Email section to provide more detail. Also made newlines at the end of sentences as per the doc guidelines.
QubesOS/qubes-issues#2070