feat(Docs): prepare for sphinx-pages (#205)

* feat(Docs): prepare for sphinx-pages

* feat(CI): added sphinx workflow

* feat(Docs): added content

* fix(CI): use the patched GH action

* fix(CI): set source dir

* chore(Docs): reorder project structure

* chore(Docs): moved index.rst one level up?

* fix(Config): restore the config file, etc.

* fix(Docs): adjusted config

docs/Makefile

@@ -0,0 +1,20 @@
+# Minimal makefile for Sphinx documentation
+#
+
+# You can set these variables from the command line, and also
+# from the environment for the first two.
+SPHINXOPTS    ?=
+SPHINXBUILD   ?= sphinx-build
+SOURCEDIR     = content
+BUILDDIR      = _build
+
+# Put it first so that "make" without argument is like "make help".
+help:
+	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+
+.PHONY: help Makefile
+
+# Catch-all target: route all unknown targets to Sphinx using the new
+# "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
+%: Makefile
+	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)