Note dependency of deb-pack

Author: c-x-berger

.travis.yml

@@ -13,7 +13,7 @@ addons:
     update: true
 arch:
   - amd64
-  - arm64 # while this technically isn't the RPi4 it's a nice proof of concept 
+  - arm64 
 cache: cargo
 before_deploy:
   - cargo deb

README.md

@@ -21,7 +21,7 @@ sudo apt update && sudo apt install libgstreamer1.0-dev \
 
 Running `cross-build.sh` with [`cross`](https://github.com/rust-embedded/cross) and Docker installed should (eventually) produce an ARM 32 executable file suitable for use with Raspbian in `target/arm7-unknown-linux-gnueabihf/release`.
 
-If you want an installable `.deb` file, run `deb-pack.sh` **after running `cross-build.sh`.**
+If you want an installable `.deb` file, run `deb-pack.sh` **after running `cross-build.sh`.** You need `dpkg` to run `deb-pack.sh`.
 
 However, `rusty-engine` is not incredibly heavyweight and can almost certainly be compiled on your Pi without the use of any particular configuration beyond [installing the dependencies.](#dependencies)