docs: add missing Makefile

docs/Makefile

@@ -0,0 +1,28 @@
+# 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
+SPHINXAUTOOPTS ?= --ignore "*.kate-swp" --ignore "**/openapi.json" --watch ../teapots_identity
+SPHINXAUTOBUILD ?= sphinx-autobuild
+SOURCEDIR = .
+BUILDDIR = _build
+
+# Put it first so that "make" without argument is like "make help".
+help:
+	@$(SPHINXBUILD) -M help "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)
+
+install:
+	pip install sphinx sphinxcontrib-mermaid furo
+
+preview:
+	@$(SPHINXAUTOBUILD) "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXAUTOOPTS) $(O)
+
+.PHONY: help preview 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)