Small improvements to documentation about qemu.

 * pointers to why we are installing from source (including a TODO)
 * added additional packages to install to the dockerfile

Note that the dockerfile changes are only tested by me locally on my
machine.

BUG=documentation

ci/Dockerfile.micro

@@ -18,7 +18,11 @@
 # CI container unnecessarily large.
 FROM python:3.10-bullseye AS qemu_builder
 RUN apt-get update
+
 RUN apt-get install -y ninja-build wget xz-utils
+RUN apt-get install -y libglib2.0-dev
+RUN apt-get install -y build-essential libcairo2-dev libpango1.0-dev libjpeg-dev libgif-dev librsvg2-dev
+
 COPY ci/install_qemu.sh ./
 # Installs all built files into /qemu_install rather than /usr/local default.
 RUN ./install_qemu.sh /tmp/qemu_install

ci/install_qemu.sh

@@ -13,6 +13,15 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 # ==============================================================================
+#
+# We are installing qemu from source because (copied from
+# https://github.com/tensorflow/tflite-micro/pull/1892#discussion_r1164316226):
+# QEMU 7.1 and above has a blocking bug
+# (https://gitlab.com/qemu-project/qemu/-/issues/1528) and that's the only
+# version available on our apt repo.
+#
+# TODO: b/285348856 - Update the version to allow for command line arguments.
+#
 # Parameters:
 # ${1} Optional. Path to install QEMU.
 LINUX_PORTABLE_URL="https://download.qemu.org/qemu-6.2.0.tar.xz"