DOC-4240 added Top-K examples (#3119)

Co-authored-by: Vladyslav Vildanov <117659936+vladvildanov@users.noreply.github.com>
Co-authored-by: ofekshenawa <104765379+ofekshenawa@users.noreply.github.com>

doctests/topk_tutorial_test.go

@@ -0,0 +1,75 @@
+// EXAMPLE: topk_tutorial
+// HIDE_START
+package example_commands_test
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/redis/go-redis/v9"
+)
+
+// HIDE_END
+
+func ExampleClient_topk() {
+	ctx := context.Background()
+
+	rdb := redis.NewClient(&redis.Options{
+		Addr:     "localhost:6379",
+		Password: "", // no password docs
+		DB:       0,  // use default DB
+	})
+
+	// REMOVE_START
+	rdb.Del(ctx, "bikes:keywords")
+	// REMOVE_END
+
+	// STEP_START topk
+	res1, err := rdb.TopKReserve(ctx, "bikes:keywords", 5).Result()
+
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Println(res1) // >>> OK
+
+	res2, err := rdb.TopKAdd(ctx, "bikes:keywords",
+		"store",
+		"seat",
+		"handlebars",
+		"handles",
+		"pedals",
+		"tires",
+		"store",
+		"seat",
+	).Result()
+
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Println(res2) // >>> [     handlebars  ]
+
+	res3, err := rdb.TopKList(ctx, "bikes:keywords").Result()
+
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Println(res3) // [store seat pedals tires handles]
+
+	res4, err := rdb.TopKQuery(ctx, "bikes:keywords", "store", "handlebars").Result()
+
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Println(res4) // [true false]
+	// STEP_END
+
+	// Output:
+	// OK
+	// [     handlebars  ]
+	// [store seat pedals tires handles]
+	// [true false]
+}