Added some breaking changes info for v4

Author: JakeGinnivan

BREAKING CHANGES.md

@@ -1,3 +1,14 @@
+v4.0.0
+ - When using GitFlow, a few things have changed. Hopefully the new settings just work for you
+    - develop has pre-release tag of `alpha` now, not unstable
+    - develop will bump as soon as a release branch is created
+    - Look at the [GitFlow examples](http://gitversion.readthedocs.io/en/latest/git-branching-strategies/gitflow-examples/) for details of how it works now
+ - Regex's are no longer used as keys in branch config
+    - We have named branches, and introduced a `regex` config which you can override.
+    - The default keys are: master, develop, feature, release, pull-request, hotfix, support
+    - Just run GitVersion.exe in your project directory and it will tell you what to change your config keys to
+    - For example, `dev(elop)?(ment)?$` is now just `develop`, we suggest not overring regex's unless you really want to use a different convention.
+
 v3.0.0
  - NextVersion.txt has been deprecated, only GitVersionConfig.yaml is supported
  - `AssemblyFileSemVer` variable removed, AssemblyVersioningScheme configuration value makes this variable obsolete

src/GitVersionCore/Configuration/ConfigurationProvider.cs

@@ -13,6 +13,7 @@ public class ConfigurationProvider
 
         public const string DefaultConfigFileName = "GitVersion.yml";
         public const string ObsoleteConfigFileName = "GitVersionConfig.yaml";
+
         public const string ReleaseBranchRegex = "releases?[/-]";
         public const string FeatureBranchRegex = "features?[/-]";
         public const string PullRequestRegex = @"(pull|pull\-requests|pr)[/-]";