Add make install target in docs/site for copying output to emscript…

…en-site (emscripten-core#9994)

docs/process.md

@@ -115,7 +115,7 @@ that is:
 
 1. In your emscripten repo checkout, enter `site`.
 2. Run `make html`.
-3. Run `cp -R build/html/* \[path-to-a-checkout-of-the-site-repo\]`
+3. Run `make install EMSCRIPTEN_SITE=\[path-to-a-checkout-of-the-site-repo\]`
 3. Go to the site repo, commit the changes, and push.
 
 [site_repo]: https://github.com/kripken/emscripten-site

site/Makefile

@@ -45,10 +45,17 @@ help:
 	@echo "  pseudoxml  to make pseudoxml-XML files for display purposes"
 	@echo "  linkcheck  to check all external links for integrity"
 	@echo "  doctest    to run all doctests embedded in the documentation (if enabled)"
+	@echo ""
+	@echo "  install    install to emscripte-site directory (set \$$(EMSCRIPTEN_SITE))"
 
 clean:
 	rm -rf $(BUILDDIR)/*
 
+install: html
+	@ if [ -z "$(EMSCRIPTEN_SITE)" ]; then echo "Please set EMSCRIPTEN_SITE"; exit 1; fi
+	rm -rf $(EMSCRIPTEN_SITE)/docs $(EMSCRIPTEN_SITE)/_images $(EMSCRIPTEN_SITE)/_source $(EMSCRIPTEN_SITE)/_start
+	cp -R $(BUILDDIR)/html/* $(EMSCRIPTEN_SITE)
+
 html:
 	$(SPHINXBUILD) -b html $(ALLSPHINXOPTS) $(BUILDDIR)/html
 	@echo