Adding a configuration for read the docs.

mps/.readthedocs.yaml

@@ -0,0 +1,16 @@
+# .readthedocs.yaml -- Build configuration for MPS manual on Read The Docs
+#
+# See https://docs.readthedocs.io/en/stable/config-file/v2.html
+
+version: 2
+
+formats: all
+
+build:
+  os: ubuntu-22.04
+  tools:
+    python: 3
+
+python:
+  install:
+    - requirements: manual/requirements.pip

mps/manual/Makefile

@@ -2,6 +2,7 @@
 # $Id$
 
 # You can set these variables from the command line.
+PYTHON        = python3
 SPHINXOPTS    =
 SPHINXBUILD   = tool/bin/sphinx-build
 PAPER         =
@@ -154,12 +155,11 @@ doctest: $(SPHINXBUILD)
 	@echo "Testing of doctests in the sources finished, look at the " \
 	      "results in $(BUILDDIR)/doctest/output.txt."
 
-tools: tool/bin/sphinx-build
+.PHONY: tools
+tools: tool/bin/pip requirements.pip
+	tool/bin/pip install -r requirements.pip
 
-tool/bin/sphinx-build: tool/bin/pip
-	tool/bin/pip install 'sphinx < 5' # Layout breaks in Sphinx >= 5.  See <https://github.com/Ravenbrook/mps/issues/121>.
-	@echo "You can now use \`make SPHINXBUILD=tool/bin/sphinx-build html' etc."
-	@echo "Or add tool/bin to your path."
+tool/bin/sphinx-build: tools
 
 tool/bin/pip:
-	python3 -mvenv tool
+	$(PYTHON) -mvenv tool

mps/manual/requirements.pip

@@ -0,0 +1,4 @@
+# manual/requirements.txt -- MPS manual build requirements for pip
+
+# Layout breaks in Sphinx >= 5.  See <https://github.com/Ravenbrook/mps/issues/121>.
+sphinx >= 4, < 5