RFR: JDK-8246750: Docs bundle should be published to common dir

[Erik Joelsson]

The jib profile for linux-x64 is currently publishing the docs_api_spec 
bundle to two locations (like most bundles a long and a short name). One 
of these locations has mistakenly been specified under the linux-x64 dir 
instead of the common dir.

Bug: https://bugs.openjdk.java.net/browse/JDK-8246750

Webrev: http://cr.openjdk.java.net/~erikj/8246750/webrev.01/

/Erik