The WebServices documentation is available as browser-based Web Help in the TAR archive format. After downloading, unpack the archive into a desired directory, for example by using the 7-Zip file archiver. Then open the file "index.html" which locates in that directory.
Please note that Internet Explorer, Chrome and Safari do not display locally-deployed Web Help files. Therefore either use Firefox or make sure that the Web Help is opened within a web server environment.