pa11y-ci now works properly when called from Make

doc/sphinx/Makefile

@@ -11,6 +11,7 @@ BUILDDIR      = _build
 VENVDIR       = $(SPHINXDIR)/venv
 PA11Y         = $(SPHINXDIR)/node_modules/pa11y-ci/bin/pa11y-ci.js --config $(SPHINXDIR)/pa11y.json
 VENV          = $(VENVDIR)/bin/activate
+HTML	      := $(shell find $(BUILDDIR) -name *.html -print0)
 
 .PHONY: help full-help woke-install pa11y-install install run html epub serve \
         clean clean-doc spelling linkcheck woke pa11y Makefile
@@ -102,9 +103,9 @@ run: install
 # Doesn't depend on $(BUILDDIR) to rebuild properly at every run.
 html: install configure
 	# Don't rebuild html if already built
-	if [ -f "../build_doc/doc/sphinx/_build/index.html" ]; then exit 0; fi; \
-	. $(VENV); \
 	cd ../build_doc/doc/sphinx; \
+	. $(VENV); \
+	if [ -f "_build/index.html" ]; then exit 0; fi; \
 	$(SPHINXBUILD) -b dirhtml "$(SOURCEDIR)" "$(BUILDDIR)" -w $(SPHINXDIR)/warnings.txt $(SPHINXOPTS)
 
 epub: install
@@ -134,8 +135,7 @@ woke: woke-install
 	    -c https://github.com/canonical/Inclusive-naming/raw/main/config.yml
 
 pa11y: pa11y-install html
-	cd ../build_doc/doc/sphinx; \
-	$(PA11Y) $(shell find $(BUILDDIR) -name *.html);
+	$(PA11Y) $(shell find ../build_doc/doc/sphinx/_build -name *.html);
 
 # Catch-all target: route all unknown targets to Sphinx using the new
 # "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).