The 6.1 User Guide (Using Liferay Portal) must be refactored to fit the directory/file structure used for LDN.
All work should be done on the 6.1.x branch of the liferay-docs repo. The current 6.1 User Guide content, found under /userGuide, can remain intact. Ant build.xml files with appropriate 6.1 properties must be created for the new User Guide's file structure. See the files under liferay-docs/discover on the master branch for these files.
Replace the old header IDs with newly generated ones.
All of the Ant build targets are in place in build-site-common.xml to test the converted Markdown files.