Ivan FB 25b0faecb8 Update networks_config.nim
When incorrect sharding config is passed, the following message can appear:

```nim
ERR 2025-07-18 10:20:44.808+02:00 validateShards failed                      topics="waku networks conf" tid=17834 file=networks_config.nim:70 error="validateShards invalid shard: 32 when numShardsInCluster: 1"
ERR 2025-07-18 10:20:44.808+02:00 Waku configuration failed                  topics="wakunode main" tid=17834 file=wakunode2.nim:56 error="validateShards invalid shard: 32 when numShardsInCluster: 1
```

This aims to reflect the exact paramater that needs to be properly configured
2025-07-18 10:28:39 +02:00
..
2025-07-18 10:28:39 +02:00