fix(spanner): mark SessionPoolConfig.MaxBurst deprecated
@@ -411,6 +411,14 @@ type SessionPoolConfig struct {
// MaxBurst is the maximum number of concurrent session creation requests.
//
+ // Deprecated: MaxBurst exists for historical compatibility and should not
+ // be used. MaxBurst was used to limit the number of sessions that the
+ // session pool could create within a time frame. This was an early safety
+ // valve to prevent a client from overwhelming the backend if a large number
+ // of sessions was suddenly needed. The session pool would then pause the
+ // creation of sessions for a while. Such a pause is no longer needed and
+ // the implementation has been removed from the pool.
+ //
// Defaults to 10.
MaxBurst uint64
