doc: fix playground.lua for Tarantool 3

We need use `box.info.replication.uuid` instead of
`box.info.cluster.uuid` to support Tarantool 3.0 [1].

1. tarantool/tarantool#8289

Part of #366
Closes #371

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Fixed
 * `crud.readview` resource cleanup on garbage collect (#379).
+* `doc/playground.lua` does not work with Tarantool 3 (#371).
 
 ## [1.3.0] - 27-09-23
 

doc/playground.lua

@@ -34,6 +34,13 @@ else
     fio.rmtree(tempdir)
 end
 
+local replicaset_uuid
+if box.info().replicaset ~= nil then
+    replicaset_uuid = box.info().replicaset.uuid
+else
+    replicaset_uuid = box.info().cluster.uuid
+end
+
 -- Setup vshard.
 _G.vshard = vshard
 box.once('guest', function()
@@ -43,7 +50,7 @@ local uri = 'guest@localhost:3301'
 local cfg = {
     bucket_count = 3000,
     sharding = {
-        [box.info().cluster.uuid] = {
+        [replicaset_uuid] = {
             replicas = {
                 [box.info().uuid] = {
                     uri = uri,