xo-unit: docs: + sphinx + breathe + expand docs

docs/install.rst

@@ -0,0 +1,62 @@
+.. _install:
+
+.. toctree
+   :maxdepth: 2
+
+Install
+=======
+
+`xo-unit source`_ lives on github.
+
+.. _xo-unit source: https://github.com/rconybea/xo-unit
+
+Implementation relies on some c++20 features (for example class-instances as template arguments).
+Tested with gcc 12.3
+
+Include as submodule
+--------------------
+
+.. code-block:: bash
+
+   cd myproject
+   git submodule add -b main https://github.com/rconybea/xo-unit ext/xo-unit
+   git submodule update --init
+
+This assumes you organize directly-incorporated dependencies under directory ``myproject/ext``.
+You would then add ``myproject/ext/xo-unit/include`` to your compiler's include path,
+and add
+
+.. code-block:: c++
+
+   #include <xo/unit/quantity.hpp>
+
+to c++ source files that rely on xo-unit
+
+Supported compilers
+-------------------
+
+* developed with gcc 12.3.0;  github CI using gcc 11.4.0 (asof March 2024)
+
+Building from source
+--------------------
+
+Although the xo-unit library is header-only, unit tests have some dependencies.
+Example instructions (github CI) for build starting from stock ubuntu are in `ubuntu-main.yml`_
+
+.. _ubuntu-main.yml: https://github.com/Rconybea/xo-unit/blob/main/.github/workflows/ubuntu-main.yml
+
+Unit test dependencies:
+
+* `catch2`_ header-only unit-test framework
+* `xo-cmake`_ cmake macros
+* `xo-indentlog`_ logging with call-structure indenting
+* `xo-refcnt`_ intrusive reference counting (needed by xo-reflect)
+* `xo-subsys`_ plugin initialization support (needed by xo-reflect)
+* `xo-reflect`_ c++ introspection library
+
+.. _catch2: https://github.com/catchorg/Catch2
+.. _xo-cmake: https://github.com/rconybea/xo-cmake
+.. _xo-indentlog: https://github.com/rconybea/indentlog
+.. _xo-refcnt: https://github.com/rconybea/refcnt
+.. _xo-subsys: https://github.com/rconybea/subsys
+.. _xo-reflect: https://github.com/rconybea/reflect