retroactively add release note for #162528 (#23177)

Author: taroface

src/current/_includes/releases/v26.2/v26.2.0-alpha.1.md

@@ -80,6 +80,7 @@ Release Date: March 11, 2026
 - The `kv.range_split.load_sample_reset_duration` cluster setting now defaults to `30m`. This should improve load-based splitting in rare edge cases. [#159499][#159499]
 - Added the `kv.protectedts.protect`, `kv.protectedts.release`, `kv.protectedts.update_timestamp`, `kv.protectedts.get_record`, and `kv.protectedts.mark_verified` metrics to track protected timestamp storage operations. These metrics help diagnose issues with excessive protected timestamp churn and operational errors. Each operation tracks both successful completions (`.success`) and failures (`.failed`, such as `ErrExists` or `ErrNotExists`). Operators can monitor these metrics to understand PTS system behavior and identify performance issues related to backups, changefeeds, and other features that use protected timestamps. [#160129][#160129]
 - Added a new metric `sql.rls.policies_applied.count` that tracks the number of SQL statements where row-level security (RLS) policies were applied during query planning. [#164405][#164405]
+- RPC connection metrics now include a `protocol` label. The following metrics are affected: `rpc.connection.avg_round_trip_latency`, `rpc.connection.failures`, `rpc.connection.healthy`, `rpc.connection.healthy_nanos`, `rpc.connection.heartbeats`, `rpc.connection.tcp_rtt`, `rpc.connection.tcp_rtt_var`, `rpc.connection.unhealthy`, `rpc.connection.unhealthy_nanos`, and `rpc.connection.inactive`. In v26.2, the label value is always `grpc`. For example: `rpc_connection_healthy{node_id="1",remote_node_id="0",remote_addr="localhost:26258",class="system",protocol="grpc"} 1` [#162528][#162528]
 - External connections can now be used with online restore. [#159090][#159090]
 - Changed goroutine profile dumps from human-readable `.txt.gz` files to binary proto `.pb.gz` files. This improves the performance of the goroutine dumper by eliminating brief in-process pauses that occurred when collecting goroutine stacks. [#160798][#160798]
 - Added a new structured event of type `rewrite_inline_hints` that is emitted when an inline-hints rewrite rule is added using `information_schema.crdb_rewrite_inline_hints`. This event is written to both the event log and the `OPS` channel. [#160901][#160901]
@@ -281,6 +282,7 @@ Release Date: March 11, 2026
 [#159286]: https://github.com/cockroachdb/cockroach/pull/159286
 [#161914]: https://github.com/cockroachdb/cockroach/pull/161914
 [#162512]: https://github.com/cockroachdb/cockroach/pull/162512
+[#162528]: https://github.com/cockroachdb/cockroach/pull/162528
 [#161230]: https://github.com/cockroachdb/cockroach/pull/161230
 [#163266]: https://github.com/cockroachdb/cockroach/pull/163266
 [#163503]: https://github.com/cockroachdb/cockroach/pull/163503