docs: add release notes

Author: kwvg

doc/release-notes-6837.md

@@ -0,0 +1,26 @@
+Statistics
+----------
+
+- IPv6 hosts are now supported by the StatsD client.
+
+- `-statshost` now accepts URLs to allow specifying the protocol, host and port in one argument.
+
+- Specifying invalid values will no longer result in silent disablement of the StatsD client and will now cause errors
+  at startup.
+
+### New Features
+
+- The StatsD client now supports TCP hosts, TCP can be opted for with the new URL syntax supported by `-statshost` (e.g.
+  `tcp://127.0.0.1:8125`). UDP (`udp://`) remains the default and will be assumed if a protocol is not specified.
+
+  - Unlike with UDP, if a TCP connection is interrupted, stats will _not_ be dropped and instead buffered according to
+    `-statsduration` and `-statsbatchsize` and flushed when connection is restored. This buffer is discarded every 5
+    minutes if connection is not restored by then.
+
+### Deprecations
+
+- `-statsport` has been deprecated and ports are now specified using the new URL syntax supported by `-statshost`.
+  `-statsport` will be removed in a future release.
+
+  - If both `-statsport` and `-statshost` with a URL specifying a port is supplied, the `-statsport` value will be
+    ignored.