added release notes

ReleaseNotes.md

@@ -1,3 +1,25 @@
+### New in 0.15.0 (released 2015/09/11)
+* New: `IRepositoryContentsClient.GetAllContents` now has an overload to support specifying a reference - #730 via @goalie7960
+* New: Support for retrieving rate limit information from `IMiscellaneousClient` - #848 via @Red-Folder
+* New: Use `GitHubClient.GetLastApiInfo()` to get API information for previous request - #855 via @Red-Folder, @khellang
+* New: `PreviousFileName` returned to show renamed files in commit - #871 via @CorinaCiocanea
+* Improved: `CommentUrl` returned on `Issue` response - #884 via @naveensrinivasan
+* Improved: Issue and Code Search now accepts multiple repositories - #835 via @shiftkey
+* Improved: Search now accepts a range of dates - #857 via @ChrisMissal
+* Improved: Documentation on `Issue` response - #876 via @Eilon
+* Improved: Code Search now accepts `FileName` parameter - #864 via @fffej
+* Fixed: `GetQueuedContent` should return empty response for `204 No Content`, instead of throwing - #862 via @haacked
+* Fixed: `TeamClient.AddMembership` sends correct parameter to server - #856 via @davidalpert
+* Obsolete: `Authorization` endpoint which does not require fingerprint - #878 via @niik
+
+**Breaking Changes:**
+ - #835 has changed the `Repos` property for `SearchIssuesRequest` and `SearchCodeRequest`
+   are now of type `RepositoryCollection` so that multiple repositories can be searched.
+ - The workarounds removed in #878 were added initially to support transitioning, but now
+   we enforce the use of a fingerprint. See https://developer.github.com/v3/oauth_authorizations/
+   for more details.
+
+
 ### New in 0.14.0 (released 2015/07/21)
 * New: Repository redirects are supported natively - #808 via @darrelmiller, @shiftkey
 * Fixed: Support for searching repositories without a search term - #828 via @alexandrugyori