Fix op category section in operations spec (#7130)

docs/ops/infrastructure/Loop_5.md

@@ -2,7 +2,7 @@
 
 **Versioned name**: *Loop-5*
 
-**Category**: Infrastructure
+**Category**: *Infrastructure*
 
 **Short description**: *Loop* operation performs recurrent execution of the network, which is described in the `body`, iterating through the data.
 The operation has similar semantic to the ONNX* Loop [operation](https://github.com/onnx/onnx/blob/master/docs/Changelog.md#Loop-13).

docs/ops/infrastructure/TensorIterator_1.md

@@ -2,7 +2,7 @@
 
 **Versioned name**: *TensorIterator-1*
 
-**Category**: Infrastructure
+**Category**: *Infrastructure*
 
 **Short description**: *TensorIterator* layer performs recurrent execution of the network, which is described in the `body`, iterating through the data.