[changed] Add two-release deprecation policy

Fixes react-bootstrap#863

CONTRIBUTING.md

@@ -82,6 +82,16 @@ Also Bootstrap mentions http://getbootstrap.com/getting-started/#examples
 as examples of things you can do, but they are not part of the core library,
 therefore this project is the wrong place to implement them.
 
+## Breaking changes
+
+Breaking changes should be accompanied with deprecations of removed
+functionality. Prior to the 1.0.0 release, we aim to follow React's example of
+taking two Minor releases to break old functionality. As such, changes that
+intend to remove or change public APIs should be be submitted against the
+`vX-rc` branch, and should be accompanied with deprecation warnings on the old
+APIs. The deprecated APIs themselves should not be removed until the Minor
+release after that.
+
 
 ## Collaborators
 

MAINTAINING.md

@@ -95,13 +95,13 @@ then be re-applied and released with the proper version bump.
 ### Release Candidates
 
 In an effort to reduce the frequency with which we introduce breaking changes we
-should do our best to first push deprecation warnings in a Minor or Patch
-release. Also, Pull Requests with breaking changes should be submitted against
-the `vX-rc` branch, where X is the next Major version. Which we will in turn
-release as an `alpha` release of the next Major version. When we are ready to
-release the next Major version bump we will merge the `vX-rc` branch into the
-`master` branch and cut a `beta` release.  Once bugs have been addressed with
-the `beta` release then we will release the Major version bump.
+should do our best to first push deprecation warnings in a Minor release. Also,
+Pull Requests with breaking changes should be submitted against the `vX-rc`
+branch, where X is the next Major version. Which we will in turn release as an
+`alpha` release of the next Major version. When we are ready to release the next
+Major version bump we will merge the `vX-rc` branch into the `master` branch and
+cut a `beta` release.  Once bugs have been addressed with the `beta` release
+then we will release the Major version bump.
 
 ### Live releasing the documentation
 

README.md

@@ -15,7 +15,7 @@
 [![devDependency Status][dev-deps-badge]][dev-deps]
 [![peerDependency Status][peer-deps-badge]][peer-deps]
 
-__Under active development - APIs will change.__ Check out the [1.0.0 Roadmap](https://github.com/react-bootstrap/react-bootstrap/wiki#100-roadmap) and [Contributing Guidelines][contributing] to see where you can help out. Prior to the 1.0.0 release, breaking changes should result in a Minor version bump.
+__Under active development - APIs will change.__ Check out the [1.0.0 Roadmap](https://github.com/react-bootstrap/react-bootstrap/wiki#100-roadmap) and [Contributing Guidelines][contributing] to see where you can help out. Prior to the 1.0.0 release, deprecations or breaking changes should result in a Minor version bump.
 
 ## Docs