decouple OASP and devonfw

[hohwille]

Currently we are working on the next big thing which is integrating everything from OASP into devonfw. From that moment in time, devonfw will be self-contained and does not depend on OASP anymore. Further, this implies that OASP is some kind of "deprecated" on the long run. However, it is still required for projects on OASP to find the existing documentation according to their release, etc.
Currently we do have a setup, where devonfw and OASP both have the same web-site. IMHO the above implies that this should change. My suggestion would be:

• devonfw.com and devon.github.io both point to the devonfw homepage from https://github.com/devonfw/devonfw.github.io - This is going to be the cool, new and shiny devonfw website telling about all the benefits and features of devonfw but no word about OASP.
• oasp.io and oasp.github.io both point to the OASP homepage from https://github.com/oasp/oasp.github.io - This website will still reflect all the old releases of OASP (esp. oasp4j - see https://github.com/oasp/oasp.github.io/tree/master/oasp4j) that are currently invisible on any of the homepages. Also the OASP homepage should contain a fat disclaimer notice that devonfw is the new OASP and therefore OASP will only get bugfixes but is going to be discontinued on the long run.