LRDOCS-327, Added Plugins SDK to /devGuide/code and added a test-resources-importer theme there; this theme is styled just like the classic Liferay theme but imports the resources from the test-resources-importer-portlet
LRDOCS-327, Updated Resources Importer section
LRDOCS-327, Added test-resources-importer-theme-6.1.20.1.war to /devGuide/code