Improve 'Quick start' documentation clarity

- Add link to OpenWrt
- Reword descriptions of system workload examples
- Rewrite one-liner Dockerfiles using heredocs

Author: struanb

README.md

@@ -62,7 +62,7 @@ NODES=3 MTU=9000 ./test
 
 ### System workloads
 
-Launch OpenWRT with port forward to LuCI web UI on port 10080:
+Launch [OpenWrt](https://openwrt.org/) with port forward to LuCI web UI on port 10080:
 
 ```console
 docker import --change='ENTRYPOINT ["/sbin/init"]' https://archive.openwrt.org/releases/23.05.2/targets/x86/generic/openwrt-23.05.2-x86-generic-rootfs.tar.gz openwrt-23.05.2 && \
@@ -71,19 +71,38 @@ echo -e "config interface 'loopback'\n\toption device 'lo'\n\toption proto 'stat
 docker run -it --rm --runtime=runcvm --name=openwrt --network=runcvm-openwrt --ip=172.128.0.5 -v /tmp/runcvm-openwrt-network:/etc/config/network -p 10080:80 openwrt-23.05.2
 ```
 
-Launch Ubuntu with Docker and [Sysbox](https://github.com/nestybox/sysbox) runtime, then within it run an Alpine _Sysbox_ container and, _within that_ install dockerd and run a container from the 'hello-world' image:
+Launch Ubuntu running Systemd and Docker with [Sysbox](https://github.com/nestybox/sysbox) runtime; then within it run an Alpine _Sysbox_ container; and, _within that_ install dockerd and run a container from the 'hello-world' image:
 
 ```console
-echo -e "FROM ubuntu:jammy\nRUN apt update && apt -y install apt-utils kmod wget iproute2 systemd ca-certificates curl gnupg udev dbus && curl -fsSL https://get.docker.com | bash\nRUN wget -O /tmp/sysbox.deb https://downloads.nestybox.com/sysbox/releases/v0.6.2/sysbox-ce_0.6.2-0.linux_amd64.deb && apt -y install /tmp/sysbox.deb\nENTRYPOINT [\"/lib/systemd/systemd\"]" | docker build --tag=ubuntu-docker-sysbox -
+cat <<EOF | docker build --tag=ubuntu-docker-sysbox -
+FROM ubuntu:jammy
+RUN apt update && apt -y install apt-utils kmod wget iproute2 systemd \
+    ca-certificates curl gnupg udev dbus && \
+    curl -fsSL https://get.docker.com | bash
+RUN wget -O /tmp/sysbox.deb \
+    https://downloads.nestybox.com/sysbox/releases/v0.6.2/sysbox-ce_0.6.2-0.linux_amd64.deb && \
+    apt -y install /tmp/sysbox.deb
+ENTRYPOINT ["/lib/systemd/systemd"]
+EOF
 docker run -d --runtime=runcvm -m 2g --name=ubuntu-docker-sysbox --env=RUNCVM_DISKS='/disks/docker,/var/lib/docker,ext4,1G;/disks/sysbox,/var/lib/sysbox,ext4,1G' ubuntu-docker-sysbox
 docker exec ubuntu-docker-sysbox bash -c "docker run --rm --runtime=sysbox-runc alpine ash -x -c 'apk add docker; dockerd &>/dev/null & sleep 5; docker run --rm hello-world'"
 docker rm -f ubuntu-docker-sysbox
 ```
 
-Launch Ubuntu with Docker and RunCVM runtime installed, then within it run an Alpine _RunCVM_ container-VM, and within that install dockerd and, _within that_, run a container from the 'hello-world' image:
+**Nested RunCVM demo** -- Launch Ubuntu running Systemd and Docker with RunCVM runtime installed; then within it run an Alpine _RunCVM_ container-VM; and, within that install dockerd and, _within that_, run a container from the 'hello-world' image:
 
 ```console
-echo -e "FROM ubuntu:jammy\nRUN apt update && apt -y install apt-utils kmod wget iproute2 systemd ca-certificates curl gnupg udev dbus && curl -fsSL https://get.docker.com | bash\nCOPY --from=newsnowlabs/runcvm:latest /opt /opt/\nRUN rm -f /etc/init.d/docker && bash /opt/runcvm/scripts/runcvm-install-runtime.sh --no-dockerd && echo kvm_intel >>/etc/modules\nENTRYPOINT [\"/lib/systemd/systemd\"]" | docker build --tag=ubuntu-docker-runcvm -
+cat <<EOF | docker build --tag=ubuntu-docker-runcvm -
+FROM ubuntu:jammy
+RUN apt update && apt -y install apt-utils kmod wget iproute2 systemd \
+    ca-certificates curl gnupg udev dbus && \
+    curl -fsSL https://get.docker.com | bash
+COPY --from=newsnowlabs/runcvm:latest /opt /opt/
+RUN rm -f /etc/init.d/docker && \
+    bash /opt/runcvm/scripts/runcvm-install-runtime.sh --no-dockerd && \
+    echo kvm_intel >>/etc/modules
+ENTRYPOINT ["/lib/systemd/systemd"]
+EOF
 docker run -d --runtime=runcvm -m 2g --name=ubuntu-docker-runcvm --env=RUNCVM_DISKS='/disks/docker,/var/lib/docker,ext4,1G' ubuntu-docker-runcvm
 docker exec ubuntu-docker-runcvm bash -c "docker run --rm --runtime=runcvm alpine ash -x -c 'apk add docker; dockerd &>/dev/null & sleep 5; docker run --rm hello-world'"
 docker rm -f ubuntu-docker-runcvm