New release name and versioning of OAM specification

[res...@gmail.com]

Hello OAMers!

Per discussed in previous community meeting about versioning of OAM spec, and based the solution we discussed in https://github.com/oam-dev/spec/issues/369.  Today we renamed OAM release from v1.0.0-alpha1 to v0.1.0 and v1.0.0-alpha2 to v0.2.0 so we can now evolve OAM spec by following Kubernetes API change convention without introducing unnecessary breaking changes in every release.

The new tags and releases have been updated in release page: https://github.com/oam-dev/spec/releases. Follow up PRs will be sent out to fix the spec doc.

Note that we will keep the v1.0.0-alpha1and v1.0.0-alpha2 tags for a graceful period  (1 month) before deleting them.

Application is the new hype!

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Lei Zhang