docs(readme): Update deb instructions to use keyring

trusted.gpg.d requires de-armored keys on some systems (Ubuntu 20.04)
and ASCII-armored keys on others (Debian 12)

README.md

@@ -102,21 +102,14 @@ key is in this repo under [deb.asc](/deb.asc).
 To install eza from this repo use:
 
 ```bash
-wget -qO- https://raw.githubusercontent.com/eza-community/eza/main/deb.asc | sudo tee /etc/apt/trusted.gpg.d/gierens.asc
-echo "deb http://deb.gierens.de stable main" | sudo tee /etc/apt/sources.list.d/gierens.list
+sudo mkdir -p /etc/apt/keyrings
+wget -qO- https://raw.githubusercontent.com/eza-community/eza/main/deb.asc | sudo gpg --dearmor -o /etc/apt/keyrings/gierens.gpg
+echo "deb [signed-by=/etc/apt/keyrings/gierens.gpg] http://deb.gierens.de stable main" | sudo tee /etc/apt/sources.list.d/gierens.list
+sudo chmod o+r /etc/apt/keyrings/gierens.gpg /etc/apt/sources.list.d/gierens.list
 sudo apt update
 sudo apt install -y eza
 ```
 
-**Note:** on some systems like Docker containers apt might require the key
-to be in dearmored format, then use this command instead:
-
-```bash
-wget -qO- https://raw.githubusercontent.com/eza-community/eza/main/deb.asc | gpg --dearmor | sudo tee /etc/apt/trusted.gpg.d/gierens.asc
-```
-
-before proceeding with the others from above.
-
 ### Nix (Linux, MacOS)
 
 [![nixpkgs unstable package](https://repology.org/badge/version-for-repo/nix_unstable/eza.svg)](https://repology.org/project/eza/versions)