Document best practice for draft release

[CharliePoole]

GRM works most smoothly if milestones and tags match the semver. One common practice is to abbreviate the milestone name and/or tag by leaving off any final .0, e.g. milestone and tag 1.5. This caused me to have some problems when the tag was eventually not found at the point of doing a production release. It seems best to use Major.Minor.Build for all purposes: milestone name, tag and in the release branch name. Telling folks to do that in advance may save them some time.