README.rst: include a separate paragraph for BIBINPUTS

The use of an external reference database isn't really a mjotex thing,
but we support it via another (previously unmentioned) environment
variable.

diff --git a/README.rst b/README.rst
index ad3c5ff57389d889212d760ce62a635eabd4abdd..36a1adf484ebf38ca7012e4385cd8e26755bede0 100644 (file)
--- a/README.rst
+++ b/README.rst
@@ -118,10 +118,28 @@ These variables are as follows:
   *not* located at build time; they must resolve relative to your
   project. Default unset.
 
-The absolute paths to the ``BIBS`` and ``MJOTEX`` entries are
-determined at build time using ``kpsewhich`` from the `kpathsea suite
+The absolute paths to the ``MJOTEX`` entries are determined at build
+time using ``kpsewhich`` from the `kpathsea suite
 <https://tug.org/texinfohtml/kpathsea.html>`_. This makes it possible
-to maintain one copy of the mjotex repository and/or one bibliography
-database, independent of your papers and presentations; but for it to
-work, those entries must live on your TeX path. See the "Installation"
-section for that.
+to maintain one copy of the mjotex repository independent of your
+papers and presentations; but for it to work, those entries must live
+on your TeX path. The "Installation" section covers this via the
+``TEXINPUTS`` and ``BSTINPUTS`` variables, for ``mjo-*.tex`` and
+``mjo.bst`` respectively.
+
+Though it has little to do with mjotex *per se*, to avoid duplication
+it is convenient to use an central (external) reference database as
+well. To facilitate this, the entries in ``BIBS`` are also located at
+build time, and again they must live on the appropriate TeX path. Now
+it is the ``BIBINPUTS`` environment variable that must be set. In your
+``~/.bashrc``:
+
+.. code-block:: shell
+
+  export BIBINPUTS="${BIBINPUTS}:/path/to/your/references"
+
+Or in your copy of ``GNUmakefile``:
+
+.. code-block:: make
+
+  export BIBINPUTS := $(BIBINPUTS):/path/to/your/references