Install JRE and csh in Docker image

These are currently needed to run lsst-texmf's acronyms.csh.

Includes doc update.

Dockerfile

@@ -7,6 +7,13 @@
 FROM lsstsqre/lsst-texlive:latest
 MAINTAINER LSST SQuaRE <sqre-admin@lists.lsst.org>
 
+# Additional dependencies for lsst-texmf (acronyms.csh)
+RUN apt-get update && \
+    apt-get install -y --no-install-recommends \
+        csh \
+        default-jre && \
+    apt-get clean
+
 # Point $TEXMFHOME to the container's lsst-texmf. This environment variable
 # exists for container runs by a user.
 ENV TEXMFHOME "/texmf"

docs/docker.rst

@@ -54,8 +54,10 @@ About the lsst-texmf Docker image
 =================================
 
 The `lsstsqre/lsst-texmf`_ Docker image is based on Ubuntu 14.04 (trusty).
-It contains a full `TeX Live`_ distribution, as well as ``make`` and ``git`` via the `lsstsqre/lsst-texlive`_ image.
+It contains a full `TeX Live`_ distribution, as well as ``make`` and ``git``, via the `lsstsqre/lsst-texlive`_ image.
+The image also contains a Java runtime for ``acronyms.csh``.
 ``lsst-texmf`` is installed in the container's ``/texmf`` directory, with :envvar:`TEXMFHOME` pre-set to that directory.
+Scripts from ``lsst-texmf``\ ’s :file:`/bin` directory are available in the container's ``PATH``.
 
 The ``latest`` tag tracks the ``master`` branch.
 Other tags may be available for pinned versions and development branches.