Add back old conf.py with warning (#279)

src/sunpy_sphinx_theme/conf.py

@@ -0,0 +1,33 @@
+"""
+This config file is kept for backwards compatibility, almost all the config has
+now been moved into the theme itself or can be imported from the main namespace
+of the theme.
+"""
+
+from sphinx.util import logging
+
+from sunpy_sphinx_theme import ON_RTD as on_rtd  # noqa: N811
+from sunpy_sphinx_theme import PNG_ICON as png_icon  # noqa: N811
+from sunpy_sphinx_theme import SVG_ICON as svg_icon  # noqa: N811
+from sunpy_sphinx_theme import get_html_theme_path
+
+_log = logging.getLogger(__name__)
+
+_log.warning(
+    "Using sunpy_sphinx_theme.conf is deprecated, please migrate to importing things you need directly from sunpy_sphinx_theme."
+)
+
+__all__ = [
+    "html_static_path",
+    "html_theme_path",
+    "html_theme",
+    "on_rtd",
+    "png_icon",
+    "svg_icon",
+]
+
+html_theme = "sunpy"
+html_theme_options = {}
+
+html_theme_path = [str(get_html_theme_path())]
+html_static_path = [str(get_html_theme_path() / "static")]