Version and Lifecycle Annotations

Use of annotations for lifecycle are inspired by Guava: https://github.com/google/guava#important-warnings

Author: benjchristensen

README.md

@@ -27,14 +27,24 @@ Learn more about RxJava on the <a href="https://github.com/ReactiveX/RxJava/wiki
 
 ## Versioning
 
-As of 1.0.0 RxJava is following semantic versioning.
-During the 0.x.y releases, the minor (.x) releases were breaking changes.
+Version 1.x is now a stable API and will be supported for several years.
 
-The 0.x releases were published under the `com.netflix.rxjava` GroupId. The 1.x releases are published under `io.reactivex`. All usage of 0.x and `com.netflix.rxjava` should eventually be migrated to 1.x and `io.reactivex`. This was done as part of the migration of the project from `Netflix/RxJava` to `ReactiveX/RxJava`.
+Minor 1.x increments (such as 1.1, 1.2, etc) will occur when non-trivial new functionality is added or significant enhancements or bug fixes occur that may have behavioral changes that may affect some edge cases (such as dependence on behavior resulting from a bug). An example of an enhancement that would classify as this is adding reactive pull backpressure support to an operator that previously did not support it. This should be backwards compatible but does behave differently.
 
-During the transition it will be possible for an application to resolve both the `com.netflix.rxjava` and `io.reactivex` artifacts. This is unfortunate but was accepted as a reasonable cost for adopting the new name as we hit version 1.0.
+Patch 1.x.y increments (such as 1.0.0 -> 1.0.1, 1.3.1 -> 1.3.2, etc) will occur for bug fixes and trivial functionality (like adding a method overload). New functionality marked with an `@Beta` or `@Experimental` annotation can also be added in patch releases to allow rapid exploration and iteration of unstable new functionality. 
+
+#### @Beta
+
+APIs marked with the `@Beta` annotation at the class or method level are subject to change. They can be modified in any way, or even removed, at any time. If your code is a library itself (i.e. it is used on the CLASSPATH of users outside your own control), you should not use beta APIs, unless you repackage them (e.g. using ProGuard, shading, etc).
+
+#### @Experimental
+
+APIs marked with the `@Experimental` annotation at the class or method level will almost certainly change. They can be modified in any way, or even removed, at any time. You should not use or rely on them in any production code. They are purely to allow broad testing and feedback. 
+
+#### @Deprecated
+
+APIs marked with the `@Deprecated` annotation at the class or method level will remain supported until the next major release but it is recommended to stop using them. 
 
-The 0.20.x branch is being maintained with bug fixes on the `com.netflix.rxjava` GroupId until version 1.0 Final is released to allow time to migrate between the artifacts.
 
 ## Full Documentation