DOC-2857 added doc code sample for TopK (#286)

tests/Doc/Topk_tutorial.cs

@@ -0,0 +1,85 @@
+// EXAMPLE: topk_tutorial
+// HIDE_START
+
+using NRedisStack.RedisStackCommands;
+using NRedisStack.Tests;
+using StackExchange.Redis;
+
+// HIDE_END
+
+// REMOVE_START
+namespace Doc;
+[Collection("DocsTests")]
+// REMOVE_END
+
+// HIDE_START
+public class Topk_tutorial
+{
+
+    [SkipIfRedis(Is.OSSCluster)]
+    public void run()
+    {
+        var muxer = ConnectionMultiplexer.Connect("localhost:6379");
+        var db = muxer.GetDatabase();
+        //REMOVE_START
+        // Clear any keys here before using them in tests.
+        db.KeyDelete("bikes:keywords");
+        //REMOVE_END
+        // HIDE_END
+
+
+        // STEP_START topk
+        bool res1 = db.TOPK().Reserve("bikes:keywords", 5, 2000, 7, 0.925);
+        Console.WriteLine(res1);    // >>> True
+
+        RedisResult[]? res2 = db.TOPK().Add("bikes:keywords",
+                "store",
+                "seat",
+                "handlebars",
+                "handles",
+                "pedals",
+                "tires",
+                "store",
+                "seat"
+        );
+
+        if (res2 is not null)
+        {
+            Console.WriteLine(string.Join(", ", string.Join(", ", res2.Select(r => $"{(r.IsNull ? "Null" : r)}"))));
+            // >>> Null, Null, Null, Null, Null, handlebars, Null, Null
+        }
+
+        RedisResult[] res3 = db.TOPK().List("bikes:keywords");
+
+        if (res3 is not null)
+        {
+            Console.WriteLine(string.Join(", ", string.Join(", ", res3.Select(r => $"{(r.IsNull ? "Null" : r)}"))));
+            // >>> store, seat, pedals, tires, handles
+        }
+
+        bool[] res4 = db.TOPK().Query("bikes:keywords", "store", "handlebars");
+        Console.WriteLine(string.Join(", ", res4)); // >>> True, False
+        // STEP_END
+
+        // Tests for 'topk' step.
+        // REMOVE_START
+        Assert.True(res1);
+        Assert.NotNull(res2);
+        Assert.Equal(
+            "Null, Null, Null, Null, Null, handlebars, Null, Null",
+            string.Join(", ", string.Join(", ", res2.Select(r => $"{(r.IsNull ? "Null" : r)}")))
+        );
+        Assert.NotNull(res3);
+        Assert.Equal(
+            "store, seat, pedals, tires, handles",
+            string.Join(", ", string.Join(", ", res3.Select(r => $"{(r.IsNull ? "Null" : r)}")))
+        );
+        Assert.Equal("True, False", string.Join(", ", res4));
+        // REMOVE_END
+
+
+        // HIDE_START
+    }
+}
+// HIDE_END
+