docs: fix removed ref to deepspeed.initialize

Author: Borda

src/lightning/fabric/strategies/deepspeed.py

@@ -598,7 +598,7 @@ def _initialize_engine(
     ) -> Tuple["DeepSpeedEngine", Optimizer]:
         """Initialize one model and one optimizer with an optional learning rate scheduler.
 
-        This calls :func:`deepspeed.initialize` internally.
+        This calls ``deepspeed.initialize`` internally.
 
         """
         import deepspeed

src/lightning/pytorch/strategies/deepspeed.py

@@ -414,7 +414,7 @@ def _setup_model_and_optimizer(
     ) -> Tuple["deepspeed.DeepSpeedEngine", Optimizer]:
         """Initialize one model and one optimizer with an optional learning rate scheduler.
 
-        This calls :func:`deepspeed.initialize` internally.
+        This calls ``deepspeed.initialize`` internally.
 
         """
         import deepspeed