[Doc] Create a new "Usage" section (#10827)

Signed-off-by: DarkLight1337 <tlleungac@connect.ust.hk>

docs/source/index.rst

@@ -85,12 +85,8 @@ Documentation
    serving/deploying_with_nginx
    serving/distributed_serving
    serving/metrics
-   serving/env_vars
-   serving/usage_stats
    serving/integrations
    serving/tensorizer
-   serving/compatibility_matrix
-   serving/faq
 
 .. toctree::
    :maxdepth: 1
@@ -99,12 +95,21 @@ Documentation
    models/supported_models
    models/adding_model
    models/enabling_multimodal_inputs
-   models/engine_args
-   models/lora
-   models/vlm
-   models/structured_outputs
-   models/spec_decode
-   models/performance
+
+.. toctree::
+   :maxdepth: 1
+   :caption: Usage
+
+   usage/lora
+   usage/multimodal_inputs
+   usage/structured_outputs
+   usage/spec_decode
+   usage/compatibility_matrix
+   usage/performance
+   usage/faq
+   usage/engine_args
+   usage/env_vars
+   usage/usage_stats
 
 .. toctree::
    :maxdepth: 1