Update docs to add `input_type` flag (#6122)

Reflect changes introduced in https://github.com/google/iree/pull/6030

Co-authored-by: CindyLiu <hcindyl@google.com>
Co-authored-by: Scott Todd <scotttodd@google.com>
diff --git a/docs/developers/developing_iree/benchmarking.md b/docs/developers/developing_iree/benchmarking.md
index ff08628..3694cf1 100644
--- a/docs/developers/developing_iree/benchmarking.md
+++ b/docs/developers/developing_iree/benchmarking.md
@@ -22,7 +22,7 @@
 $ bazel run //iree/tools:iree-translate -- \
   -iree-mlir-to-vm-bytecode-module \
   -iree-hal-target-backends=vmvx \
-  $PWD/iree/tools/test/iree-benchmark-module.mlir \
+  $PWD/iree/samples/models/simple_abs.mlir \
   -o /tmp/module.fb
 ```
 
@@ -33,7 +33,7 @@
   --module_file=/tmp/module.fb \
   --driver=vmvx \
   --entry_function=abs \
-  --function_input=i32=-2
+  --function_input=f32=-2
 ```
 
 You'll see output like
@@ -80,7 +80,7 @@
   --module_file=/tmp/module.fb \
   --driver=vmvx \
   --entry_function=abs \
-  --function_input=i32=-2
+  --function_input=f32=-2
 ```
 
 ```shell
@@ -108,6 +108,7 @@
 
 ```shell
 $ build/iree/tools/iree-translate \
+  -iree-input-type=mhlo \
   -iree-mlir-to-vm-bytecode-module \
   -iree-flow-export-benchmark-funcs \
   -iree-hal-target-backends=vmvx \