util/docker: Update container for doc.coreboot.org

Now running 1.8.3, with a fix to the theme so search still works, and
a recommonmark version that properly rewrites links to .md files.

Change-Id: Ice25554c77a398a71782c8d1cb9e205debd80d67
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/31129
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>

util/docker/doc.coreboot.org/Dockerfile

@@ -5,9 +5,9 @@ COPY makeSphinx.sh /makeSphinx.sh
 RUN apk add --no-cache python3 make bash git \
  && pip3 install --upgrade --no-cache-dir pip \
  && pip3 install --no-cache-dir  \
-    sphinx===1.7.7 \
-    sphinx_rtd_theme===0.4.1 \
-    recommonmark===0.4.0 \
+    sphinx===1.8.3 \
+    sphinx_rtd_theme===0.4.2 \
+    recommonmark===0.5.0 \
     sphinx_autobuild===0.7.1 \
  && chmod 755 /makeSphinx.sh