Adding release approval policy AND call for approval of V.2.0.0 (#234)

* Adding release approval

* Update README.md

I added a few qualifiers in response to some concerns raised on the PR

* Update README.md

OK...I added something about giving notice.

README.md

@@ -6,6 +6,8 @@ This repository is the public home of all standardization work for Uptane.
 
 As the Standard is a living document, updates are made in real time as needed. However, these changes will not be considered formally adopted until the release of the next minor or major version.
 
+Major and minor release dates are set by the Uptane Standards committee. All final releases will be approved by the committee, either by voice vote at a designated bimonthly meeting of the Uptane Standard group or by responding "approve" in a designated mailing list or repository thread. A release will be deemed approved if it receives a simple majority of positive responses by active group members. "Active" here is defined as an individual who regularly appears at bimonthly meetings, or participates in the preparation or review of pull requests, or engages in discussion of issues on the mailing list threads. Upcoming votes will be announced at least two weeks prior to taking or finalizing votes.
+
 ## Existing documentation
 
 The Uptane Standards document should be considered the authoritative resource for the framework. Several other documents and materials are available or currently in development. The information in all of these other guidelines should be viewed as complementary to the official Uptane Standard, and as recommendations rather than mandatory instructions.