relase_notes: add release notes for v0.34.0

release_notes.md

@@ -1 +1,4 @@
-<!-- TODO: add in release notes prior to release. -->
+Tendermint Core v0.34.0 is the Tendermint Core release which supports the Stargate upgrade. 
+
+For more information on how to upgrade to Tendermint 0.34, please see [UPGRADING.md](https://github.com/tendermint/tendermint/blob/release/v0.34.0/UPGRADING.md). 
+For a full list of user-facing changes, please see [CHANGELOG.md](https://github.com/tendermint/tendermint/blob/release/v0.34.0/CHANGELOG.md).