Fix api spec checksum

* Update api checksum to fix the build
* Update the README with correct instructions for generating the api doc

[#71937450]

Signed-off-by: Michael Fraenkel <fraenkel@us.ibm.com>
Update ruby to 1.9.3-p547

[#71367862]

Signed-off-by: Michael Fraenkel <fraenkel@us.ibm.com>