README: "Building from source" apt-get example is missing meson and ninja-build

[caffentrager]

The Dependencies list under Building from source says meson (>= 0.64) and ninja are required:

• meson version 0.64 or higher
• ninja

But the Debian/Ubuntu apt-get install example right below it doesn't include them:

sudo apt-get update && sudo apt-get install -y \
python3 python3-pip python3-setuptools python3-wheel \
cmake make build-essential \
libpam0g-dev libinih-dev libevdev-dev python3-opencv \
python3-dev libopencv-dev

Following the README as written, meson setup build fails with command not found right after this step. Also worth noting: on Debian/Ubuntu the apt package for ninja is named ninja-build, not ninja.

Suggested fix — add meson ninja-build to the apt-get line:

sudo apt-get update && sudo apt-get install -y \
meson ninja-build \
python3 python3-pip python3-setuptools python3-wheel \
cmake make build-essential \
libpam0g-dev libinih-dev libevdev-dev python3-opencv \
python3-dev libopencv-dev

Happy to send a one-line PR for this if preferred — figured I'd flag it first since it's such a small change.