- Added `chmod 644 /etc/apt/keyrings/bruno.gpg` so `_apt` user can read the key
- Keeps key in binary format with `gpg --dearmor`
- Prevents NO_PUBKEY errors and repository being ignored on Debian 12+
- Added introduction of commercial version
- Added Table of Contents
- Updated installation guide via package managers
- Updated important links
- Adjusted document structure, optimized title hierarchy
- Add instructions to install gpg;
- Use "gpg --list-keys" to let gpg create ".gnupg" directory with correct rights;
- Use "arch=amd64" - see commit 6c8c87fe28.
