It gets *.TXT, and thus a README.TXT, but that's actually a doxygen explanation of codebase layout that doesnt really pertain to use of the program itself. abi/user/wp contains a more germane readme.txt, though be aware that the one in 1.99.1 and prior is as up to date as abiword-0.7. That's been fixed in cvs and the new documentation will be in 1.99.2 (second beta) which is due Real Soon Now.
added the readme.txt to the dodoc as well in the 1.99.2 ebuild.