Update docs

Author: sethrj

doc/implementation/core-physics/stepping.rst

@@ -58,8 +58,9 @@ single "action" class can, for example, allocate states at the beginning of the
 run and execute once per step.
 
 There are currently two different actions that act as extension points to the
-stepping loop: :cpp:class:`BeginRunActionInterface` is called once per event
-(or set of simultaneously initialized events), and :cpp:class:`StepActionInterface`
+stepping loop: :cpp:class:`celeritas::BeginRunActionInterface` is called once
+per event
+(or set of simultaneously initialized events), and :cpp:class:`celeritas::StepActionInterface`
 is called once per step, ordered using :cpp:enum:`celeritas::StepActionOrder`.
 
 .. doxygenclass:: celeritas::ActionInterface

doc/implementation/corecel.rst

@@ -89,15 +89,30 @@ incorrect configuration or input values.
 System
 ------
 
+The system subdirectory provides uniform interfaces to hardware and the
+operating system.
+
+GPU management
+^^^^^^^^^^^^^^
+
 .. doxygenclass:: celeritas::Device
 .. doxygenfunction:: celeritas::device
 .. doxygenfunction:: celeritas::activate_device()
 
+Environment variables
+^^^^^^^^^^^^^^^^^^^^^
+
 .. doxygenclass:: celeritas::Environment
 .. doxygenfunction:: celeritas::environment
 .. doxygenfunction:: celeritas::getenv
 .. doxygenfunction:: celeritas::getenv_flag
 
+MPI support
+^^^^^^^^^^^
+
+.. doxygenclass:: celeritas::ScopedMpi
+.. doxygenclass:: celeritas::MpiCommunicator
+
 Utility functions
 -----------------
 

doc/implementation/geant4-interface.rst

@@ -17,6 +17,11 @@ advanced implementation can be inspected in the :ref:`celer-g4` app.
 High level interfaces
 ---------------------
 
+The high-level integration classes are the easiest way to add Celeritas to a
+Geant4 application. Under the hood, it contains a singleton class instance that
+sets up the UI commands (see :cpp:class:`celeritas::SetupOptionsMessenger`),
+MPI (if configured), and Celeritas logging.
+
 .. doxygenclass:: celeritas::IntegrationBase
    :members:
    :no-link:
@@ -31,7 +36,7 @@ manager correctly, we recommend using this helper class:
 
 .. doxygenclass:: celeritas::TrackingManagerConstructor
 
-The high-level :cpp:class:`TrackingManagerIntegration` class should be used in
+The high-level :cpp:class:`celeritas::TrackingManagerIntegration` class should be used in
 addition to the tracking manager constructor to set up and tear down Celeritas.
 See :ref:`example_template` for a template of adding to a user application.
 
@@ -114,9 +119,9 @@ compatible with Celeritas), the Celeritas setup will fail with an error like:
 .. doxygenclass:: celeritas::RZMapFieldAlongStepFactory
 
 
-The :cpp:class:`SetupOptionsMessenger`, instantiated automatically by the
-Integration helper classes, provides a Geant4 "UI" macro interface to many of
-the options.
+The :cpp:class:`celeritas::SetupOptionsMessenger`, instantiated automatically
+by the Integration helper classes, provides a Geant4 "UI" macro interface to
+many of the options.
 
 .. doxygenclass:: celeritas::SetupOptionsMessenger
 

doc/implementation/orange.rst

@@ -22,7 +22,7 @@ Intersect region
 ^^^^^^^^^^^^^^^^
 
 The lowest level primitive for construction is the "intersect region," which is
-a CSG intersection of half-spaces. The :cpp:class:`IntersectRegion` interface
+a CSG intersection of half-spaces. The IntersectRegion interface
 helps construct these objects.
 
 .. doxygenclass:: celeritas::orangeinp::IntersectRegionInterface