Add wg-diagnostics meeting notes

Author: oli-obk

working-groups/diagnostics/NOTES.md

@@ -1,3 +1,8 @@
 # Diagnostics Meeting Notes
-This document will contain meeting notes from the diagnostics working group.
+
+# 2019-05-24
+* [zulip link](https://rust-lang.zulipchat.com/#narrow/stream/147480-t-compiler.2Fwg-diagnostics/topic/meeting.202019-05-24)
+* We triaged all `P-medium` `A-diagnostics` issues
+* We figured out a first action for getting `annotate-snippets` into rustc: https://github.com/rust-lang/rust/issues/59346
+* We have a plan to reduce the boilerplate needed at the diagnostic emitter site: https://github.com/rust-lang/rust/issues/61132