Fix docs filterwarnings snippet (#10671)

Author: carmocca

docs/source/guides/speed.rst

@@ -151,9 +151,7 @@ For debugging purposes or for dataloaders that load very small datasets, it is d
 
     import warnings
 
-    warnings.filterwarnings(
-        "ignore", ".*does not have many workers. Consider increasing the value of the `num_workers` argument*"
-    )
+    warnings.filterwarnings("ignore", ".*Consider increasing the value of the `num_workers` argument*")
 
 Spawn
 """""

pytorch_lightning/trainer/data_loading.py

@@ -107,6 +107,7 @@ def _worker_check(self, dataloader: DataLoader, name: str) -> None:
                 )
 
         elif dataloader.num_workers <= 2 < num_cpus and not using_spawn:
+            # if changed, update the `filterwarnings` snippet in 'speed.html#num-workers'
             rank_zero_warn(
                 f"The dataloader, {name}, does not have many workers which may be a bottleneck."
                 " Consider increasing the value of the `num_workers` argument`"