docs: add readme in component directory (#6699)

components/src/dynamo/global_planner/README.md

+<!-- # SPDX-FileCopyrightText: Copyright (c) 2025-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0 -->
+
+# Global Planner
+
+Centralized scaling execution service for hierarchical planner deployments.
+
+The Global Planner receives scaling decisions from distributed planners and executes
+replica updates against Kubernetes `DynamoGraphDeployment` resources.
+
+## Overview
+
+- Exposes a remote scaling endpoint for planner delegation
+- Optionally authorizes caller namespaces
+- Executes scaling through `KubernetesConnector`
+- Returns operation status and observed replica counts
+- Supports dry-run mode via `--no-operation`
+
+## Runtime Endpoints
+
+Given `DYN_NAMESPACE=<ns>`, this component serves:
+
+- `<ns>.GlobalPlanner.scale_request`
+- `<ns>.GlobalPlanner.health`
+
+`health` returns:
+
+- `status` (`healthy`)
+- `component` (`GlobalPlanner`)
+- `namespace`
+- `managed_namespaces` (`all` when authorization is disabled)
+
+## Usage
+
+### Command Line
+
+```bash
+# Accept scale requests from any namespace
+DYN_NAMESPACE=global-infra python -m dynamo.global_planner
+```
+
+```bash
+# Restrict requests to specific planner namespaces
+DYN_NAMESPACE=global-infra python -m dynamo.global_planner \
+  --managed-namespaces app-ns-1 app-ns-2
+```
+
+```bash
+# Dry-run mode (no Kubernetes updates)
+DYN_NAMESPACE=global-infra python -m dynamo.global_planner --no-operation
+```
+
+### Arguments
+
+Required environment variables:
+
+- `DYN_NAMESPACE`: Dynamo namespace used to register runtime endpoints.
+
+Optional environment variables:
+
+- `POD_NAMESPACE`: Kubernetes namespace where Global Planner runs (defaults to `default` if unset).
+
+CLI arguments:
+
+- `--managed-namespaces <ns1> <ns2> ...`: Allowlist for `caller_namespace`. If omitted, accepts all namespaces.
+- `--environment kubernetes`: Execution environment (currently only `kubernetes` is supported).
+- `--no-operation`: Log incoming scale requests and return success without applying Kubernetes scaling.
+
+## Scale Request Contract
+
+The `scale_request` endpoint consumes `ScaleRequest` and returns `ScaleResponse`.
+
+Request fields:
+
+- `caller_namespace` (string): Namespace identity of the planner sending the request
+- `graph_deployment_name` (string): Target `DynamoGraphDeployment` name
+- `k8s_namespace` (string): Kubernetes namespace of the target deployment
+- `target_replicas` (list): Desired replica targets
+- `blocking` (bool, default `false`): Wait for scaling completion
+- `timestamp` (optional float): Caller-provided request timestamp
+- `predicted_load` (optional object): Caller-provided prediction context
+
+`target_replicas` entries use:
+
+- `sub_component_type`: `prefill` or `decode`
+- `desired_replicas`: integer replica target
+- `component_name`: optional component override
+
+Response fields:
+
+- `status`: `success` or `error`
+- `message`: status detail
+- `current_replicas`: map of observed replicas, for example `{"prefill": 3, "decode": 5}`
+
+## Behavior
+
+- If `--managed-namespaces` is set and `caller_namespace` is not authorized, Global Planner returns `error` and does not scale.
+- In `--no-operation` mode, Global Planner logs the request and returns `success` with empty `current_replicas`.
+
+## Related Documentation
+
+- [Planner Guide](../../../../docs/components/planner/planner-guide.md) — Planner configuration and deployment workflow
+- [Planner Design](../../../../docs/design-docs/planner-design.md) — Planner architecture and algorithms
+
+Planners delegate to this service when planner config uses `environment: "global-planner"` and sets `global_planner_namespace`.
\ No newline at end of file

components/src/dynamo/sglang/README.md

+<!-- # SPDX-FileCopyrightText: Copyright (c) 2024-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0 -->
+
+# SGLang
+
+See [docs/backends/sglang/](../../../../docs/backends/sglang/README.md) for documentation.

components/src/dynamo/trtllm/README.md

+<!-- # SPDX-FileCopyrightText: Copyright (c) 2024-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0 -->
+
+# TensorRT-LLM
+
+See [docs/pages/backends/trtllm/](../../../../docs/backends/trtllm/README.md) for documentation.

components/src/dynamo/vllm/README.md

+<!-- # SPDX-FileCopyrightText: Copyright (c) 2024-2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+# SPDX-License-Identifier: Apache-2.0 -->
+
+# vLLM
+
+See [docs/backends/vllm/](../../../../docs/backends/vllm/README.md) for documentation.