set fp16 to false if bf16, update bf16: auto in example YAMLs (#1122) [skip ci]

* set fp16 to false if bf16, update bf16: auto in example YAMLs

* unset fp16 so that it fallsback properly if bf16 isn't available

* Update README.md [skip-ci]

Co-authored-by: NanoCode012 <kevinvong@rocketmail.com>

* test that bf16 disables fp16

---------

Co-authored-by: NanoCode012 <kevinvong@rocketmail.com>

examples/phi/phi-ft.yml

@@ -46,8 +46,8 @@ learning_rate: 0.000003
 
 train_on_inputs: false
 group_by_length: true
-bf16: true
-fp16: false
+bf16: auto
+fp16:
 tf32: true
 
 gradient_checkpointing:

examples/phi/phi-qlora.yml

@@ -46,8 +46,8 @@ learning_rate: 0.000003
 
 train_on_inputs: false
 group_by_length: true
-bf16: true
-fp16: false
+bf16: auto
+fp16:
 tf32: true
 
 gradient_checkpointing:

examples/phi/phi2-ft.yml

@@ -49,8 +49,8 @@ learning_rate: 1e-5
 
 train_on_inputs: false
 group_by_length: false
-bf16: true
-fp16: false
+bf16: auto
+fp16:
 tf32: true
 
 gradient_checkpointing: true