Google "acrobat help".
At the top of the query return page use the link "Acrobat Help" which takes you to:
Links to Help and tutorials are located in the upper right.
Click the link for "Acrobat Pro help".
You'll land on the livedocs Help page for Acrobat X Pro.
This is the content that is actively updated.
You can download a PDF (link located in upper right).