[Doc][4/N] Reorganize API Reference (#11843)

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

docs/source/api/multimodal/index.md

@@ -0,0 +1,73 @@
+(multi-modality)=
+
+# Multi-Modality
+
+```{eval-rst}
+.. currentmodule:: vllm.multimodal
+```
+
+vLLM provides experimental support for multi-modal models through the {mod}`vllm.multimodal` package.
+
+Multi-modal inputs can be passed alongside text and token prompts to [supported models](#supported-mm-models)
+via the `multi_modal_data` field in {class}`vllm.inputs.PromptType`.
+
+Looking to add your own multi-modal model? Please follow the instructions listed [here](#enabling-multimodal-inputs).
+
+
+## Module Contents
+
+```{eval-rst}
+.. automodule:: vllm.multimodal
+```
+
+### Registry
+
+```{eval-rst}
+.. autodata:: vllm.multimodal.MULTIMODAL_REGISTRY
+```
+
+```{eval-rst}
+.. autoclass:: vllm.multimodal.MultiModalRegistry
+    :members:
+    :show-inheritance:
+```
+
+### Base Classes
+
+```{eval-rst}
+.. automodule:: vllm.multimodal.base
+    :members:
+    :show-inheritance:
+```
+
+### Input Classes
+
+```{eval-rst}
+.. automodule:: vllm.multimodal.inputs
+    :members:
+    :show-inheritance:
+```
+
+### Audio Classes
+
+```{eval-rst}
+.. automodule:: vllm.multimodal.audio
+    :members:
+    :show-inheritance:
+```
+
+### Image Classes
+
+```{eval-rst}
+.. automodule:: vllm.multimodal.image
+    :members:
+    :show-inheritance:
+```
+
+### Video Classes
+
+```{eval-rst}
+.. automodule:: vllm.multimodal.video
+    :members:
+    :show-inheritance:
+```