Release notes lists all the changes of the each API version. Use them to check whether your application is compatible with specific API version, and what changes you might need to make before you migrate your app with the newer version.
New version will be released every 3months, at the beginning of the quarter at 5AM in UTC timezone.
However, if there were no breaking changes made within the period, it could be postponed to the next release date.
Each version will be deprecated after 9 months from the next version release. For example, v1.0 will be deprecated 9 months after v1.1 release. Hence, each version will be supported at least for 12 months.