Update ReleaseNotes

docs/ReleaseNotes.md

 # Mongoose Release Notes
 
+## Release 5.6, 2015-03-17
+
+Changes in Libmongoose library:
+
+- Added `-dav_root` configuration option that gives an ability to mount
+  a different root directory (not document_root)
+- Fixes for build under Win23 and MinGW
+- Bugfix: Double dots removal
+- Bugfix: final chunked response double-send
+- Fixed compilation in 64-bit environments
+- Added OS/2 compatibility
+- Added `getaddrinfo()` call and `NS_ENABLE_GETADDRINFO`
+- Various SSL-related fixes
+- Added integer overflow protection in `iobuf_append()` and `deliver_websocket_frame()`
+- Fixed NetBSD build
+- Enabled `NS_ENABLE_IPV6` build for Visual Studio 2008+
+- Enhanced comma detection in `parse_header()`
+- Fixed unchanged memory accesses on ARM
+- Added ability to use custom memory allocator through NS_MALLOC, NS_FREE, NS_REALLOC
+
+Changes in Mongoose binary:
+
+- Added `-start_browser` option to disable automatic browser launch
+- Added SSL support to DEV edition
+
 ## Release 5.5, October 28 2014
 
 Changes in Libmongoose library: