Disable to open a browser window after making docs.

Signed-off-by: Daniel Scheffler <danschef@gfz-potsdam.de>

Makefile

@@ -107,8 +107,8 @@ docs: ## generate Sphinx HTML documentation, including API docs
 	 $(MAKE) -C docs clean
 	 $(MAKE) -C docs html
 	#$(MAKE) -C docs latex
-#	$(MAKE) -C docs latexpdf
-	$(BROWSER) docs/_build/html/index.html
+	#$(MAKE) -C docs latexpdf
+	#$(BROWSER) docs/_build/html/index.html
 
 servedocs: docs ## compile the docs watching for changes
 	watchmedo shell-command -p '*.rst' -c '$(MAKE) -C docs html' -R -D .