docs: Add detailed docstrings to API models and update OpenAPI spec (#2889)

This PR focuses on improving the developer experience by adding
comprehensive docstrings to the API data models across the Llama Stack.
These docstrings provide detailed explanations for each model and its
fields, making the API easier to understand and use.

**Key changes:**
- **Added Docstrings:** Added reST formatted docstrings to Pydantic
models in the `llama_stack/apis/` directory. This includes models for:
  - Agents (`agents.py`)
  - Benchmarks (`benchmarks.py`)
  - Datasets (`datasets.py`)
  - Inference (`inference.py`)
  - And many other API modules.
- **OpenAPI Spec Update:** Regenerated the OpenAPI specification
(`docs/_static/llama-stack-spec.yaml` and
`docs/_static/llama-stack-spec.html`) to include the new docstrings.
This will be reflected in the API documentation, providing richer
information to users.

**Impact:**
- Developers using the Llama Stack API will have a better understanding
of the data structures.
- The auto-generated API documentation is now more informative.

---------

Co-authored-by: Ashwin Bharambe <ashwin.bharambe@gmail.com>

llama_stack/apis/safety/safety.py

@@ -17,6 +17,13 @@ from llama_stack.schema_utils import json_schema_type, webmethod
 
 @json_schema_type
 class ViolationLevel(Enum):
+    """Severity level of a safety violation.
+
+    :cvar INFO: Informational level violation that does not require action
+    :cvar WARN: Warning level violation that suggests caution but allows continuation
+    :cvar ERROR: Error level violation that requires blocking or intervention
+    """
+
     INFO = "info"
     WARN = "warn"
     ERROR = "error"
@@ -24,6 +31,13 @@ class ViolationLevel(Enum):
 
 @json_schema_type
 class SafetyViolation(BaseModel):
+    """Details of a safety violation detected by content moderation.
+
+    :param violation_level: Severity level of the violation
+    :param user_message: (Optional) Message to convey to the user about the violation
+    :param metadata: Additional metadata including specific violation codes for debugging and telemetry
+    """
+
     violation_level: ViolationLevel
 
     # what message should you convey to the user
@@ -36,6 +50,11 @@ class SafetyViolation(BaseModel):
 
 @json_schema_type
 class RunShieldResponse(BaseModel):
+    """Response from running a safety shield.
+
+    :param violation: (Optional) Safety violation detected by the shield, if any
+    """
+
     violation: SafetyViolation | None = None