Add release notes for v0.5.1

Co-authored-by: Roberto Abdelkader Martínez Pérez <robertomartinezp@gmail.com>

docs/release-notes/RELEASE-v0.5.1.md

@@ -0,0 +1,39 @@
+Kapow! v0.5.1
+
+## Features
+
+* Re-release of v0.5.0 with missing release-key.gpg added, as well as debugging doc example
+
+* [#89][i89] Wrong environment variables exported to process
+
+* [#98][i98] Implement a proper logging system (Partially solved. Added a logging feature for scripts in User-server for aid in debugging)
+
+* [#92][i92] Spawn package uses static default value for KAPOW_DATA_URL
+
+* [#102][i102] Handle race condition between Control API and pow files
+
+* [#105][i105] Handle unexpected exit of servers
+
+
+## Known issues and limitations
+
+### Data API
+
+* [#73][i73] `/response/body` and `/response/stream` behave identically for now.
+
+
+### Windows®
+
+* [#83][i83] `kapow server file.pow` will try to run `file.pow` through `bash`, not `cmd`
+  or `powershell`.
+* `kapow route` default entrypoint is `/bin/sh`, so in order to use `cmd` or
+  `powershell`, it must be explicitly set.
+
+
+[i73]: https://github.com/BBVA/kapow/issues/73
+[i83]: https://github.com/BBVA/kapow/issues/83
+[i89]: https://github.com/BBVA/kapow/issues/89
+[i98]: https://github.com/BBVA/kapow/issues/98
+[i92]: https://github.com/BBVA/kapow/issues/92
+[i102]: https://github.com/BBVA/kapow/issues/102
+[i105]: https://github.com/BBVA/kapow/issues/105