Update the code-snippets in the documentation (#2716)

Signed-off-by: polly-updater-bot[bot] <138034000+polly-updater-bot[bot]@users.noreply.github.com>
Co-authored-by: polly-updater-bot[bot] <138034000+polly-updater-bot[bot]@users.noreply.github.com>

Author: polly-updater-bot[bot]

docs/strategies/retry.md

@@ -487,9 +487,7 @@ ImmutableArray<Type> strategyExceptions =
     typeof(RateLimitRejectedException),
 ];
 
-ImmutableArray<Type> retryableExceptions = networkExceptions
-    .Union(strategyExceptions)
-    .ToImmutableArray();
+ImmutableArray<Type> retryableExceptions = [.. networkExceptions.Union(strategyExceptions)];
 
 var retry = new ResiliencePipelineBuilder()
     .AddRetry(new()