util/docker: Update dockerfiles

- Remove deprecated "MAINTAINER" lines
- Add Sphinx tools to coreboot-jenkins-node to check documentation.
- Add mdl to check markdown
- Alphabetize packages in docs Dockerfile
- Add jinja2 version 3.0.3 to the docs Dockerfile - The latest version
breaks with the error:
"exception: cannot import name 'contextfunction' from 'jinja2'"

Signed-off-by: Martin Roth <gaumless@gmail.com>
Change-Id: Ia1de62621a6aef4ecd055a1a3afbebad34448002
Reviewed-on: https://review.coreboot.org/c/coreboot/+/64655
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Singer <felixsinger@posteo.net>

util/docker/doc.coreboot.org/Dockerfile

@@ -7,12 +7,14 @@ ADD https://sourceforge.net/projects/ditaa/files/ditaa/0.9/ditaa0_9.zip/download
 RUN apk add --no-cache python3 make bash git openjdk8-jre ttf-dejavu fontconfig \
  && pip3 install --upgrade --no-cache-dir pip \
  && pip3 install --no-cache-dir  \
-    sphinx===1.8.3 \
-    sphinx_rtd_theme===0.4.2 \
-    recommonmark===0.5.0 \
-    sphinx_autobuild===0.7.1 \
-    sphinxcontrib-ditaa===0.6 \
+  jinja2==3.0.3 \
+  recommonmark===0.5.0 \
+  sphinx===1.8.3 \
+  sphinxcontrib-ditaa===0.6 \
+  sphinx_autobuild===0.7.1 \
+  sphinx_rtd_theme===0.4.2 \
  && chmod 755 /makeSphinx.sh
+
 RUN cd /tmp \
  && unzip ditaa.zip \
  && mv ditaa0_9.jar /usr/lib