add notes about EOS_DIR and NETWORK_DIR and index them

Author: zingale

Docs/source/eos_implementations.rst

@@ -2,10 +2,15 @@
 Available Equations of State
 ****************************
 
-.. index:: eos_t
+.. index:: eos_t, EOS_DIR
 
 The following equations of state are available in Microphysics.
 
+.. note::
+
+   The EOS is chosen at compile-time via the ``EOS_DIR`` make
+   variable.
+
 .. note::
 
    Except where noted, each of these EOSs will provide the full

Docs/source/networks.rst

@@ -7,6 +7,13 @@ of state and transport coefficient routines.  Even if there are no
 reactions taking place, a network still needs to be defined, so
 Microphysics knows the properties of the fluid.
 
+.. index:: NETWORK_DIR
+
+.. note::
+
+   The network is set at compile-time via the ``NETWORK_DIR``
+   make variable.
+
 .. tip::
 
    If reactions can be ignored, then the ``general_null`` network can
@@ -21,6 +28,8 @@ Microphysics knows the properties of the fluid.
 ``general_null``
 ================
 
+.. index:: general_null
+
 ``general_null`` is a bare interface for a nuclear reaction network ---
 no reactions are enabled. The
 data in the network is defined at compile type by specifying an