update title level (#2969)

Co-authored-by: liuzhe-lz <40699903+liuzhe-lz@users.noreply.github.com>
Co-authored-by: colorjam <im.cqyan@google.com>

docs/en_US/Compression/CompressionUtils.md

@@ -120,7 +120,7 @@ from nni.compression.torch.utils.mask_conflict import fix_mask_conflict
 fixed_mask = fix_mask_conflict('./resnet18_mask', net, data)
 ```
 
-### Model FLOPs/Parameters Counter
+## Model FLOPs/Parameters Counter
 We provide a model counter for calculating the model FLOPs and parameters. This counter supports calculating FLOPs/parameters of a normal model without masks, it can also calculates FLOPs/parameters of a model with mask wrappers, which helps users easily check model complexity during model compression on NNI. Note that, for sturctured pruning, we only identify the remained filters according to its mask, which not taking the pruned input channels into consideration, so the calculated FLOPs will be larger than real number (i.e., the number calculated after Model Speedup).
 
 ### Usage