The primary documentation for the various CEPR data extracts are the programs themselves. They provide an exact description of the definition of each of the variables and, in most cases, are heavily annotated.
The Census Bureau has produced a great deal of useful documentation about the CPS Outgoing Rotation Group (ORG). The best place to start is the joint Census-BLS CPS home page.
For each year, the Census provides Codebooks and Data Dictionaries to help understand each variable.
For documentation, see the CEPR CPS Basic Documentation page.