Please find the link below and let me know incase of any concerns.
11.4 - Features and Enhancements - http://docs.oracle.com/cd/E14902_01/v114feat.pdf
11.5 - Features and Enhancements - http://docs.oracle.com/cd/E15200_01/v113p05feat.pdf
Release notes for 11.5 is available in Oracle's Documaker Studio 11.5 url itself (first link):
For the prior versions, you can look for document titled "Features and Enhancements" (FEAT) to get relevant information. It is the same for Docupresentment versions as well. "Features and Enhancements" (FEAT) document pretty much gives information releated to what was released in that version.