README: document deb-dist as Install option

The Makefile has target 'deb-dist' for building a Debian package.
Now is the README.md aware of it, it is added to the Install section.

Signed-off-by: Geert Stappers <stappers@stappers.it>

README.md

@@ -26,6 +26,7 @@ Try an [old online interactive web demo](https://meli-email.org/wasm2.html "onli
 - [pkgsrc](https://pkgsrc.se/mail/meli)
 - [openbsd ports](https://openports.pl/path/mail/meli)
 - `cargo install meli` or `cargo install --git https://git.meli-email.org/meli/meli.git meli`
+- `make deb-dist  &&  sudo dpkg --install ../meli_*.deb`
 - [Pre-built debian package, static binaries](https://github.com/meli/meli/releases/ "github releases for meli")
 - [Nix](https://search.nixos.org/packages?show=meli&query=meli&from=0&size=30&sort=relevance&channel=unstable#disabled "nixos package search results for 'meli'")