docs(planning-design): add planning internal interface (autowarefound…

…ation#390)

* docks(planning-design): add planning internal interface

Signed-off-by: Takamasa Horibe <horibe.takamasa@gmail.com>

* Update docs/design/autoware-interfaces/components/planning.md

Co-authored-by: Maxime CLEMENT <78338830+maxime-clem@users.noreply.github.com>

* Update docs/design/autoware-architecture/planning/index.md

Co-authored-by: Maxime CLEMENT <78338830+maxime-clem@users.noreply.github.com>

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Signed-off-by: Takamasa Horibe <horibe.takamasa@gmail.com>
Co-authored-by: Maxime CLEMENT <78338830+maxime-clem@users.noreply.github.com>
Signed-off-by: guiping meng <alan.meng@autocore.ai>

docs/design/autoware-architecture/planning/index.md

@@ -44,7 +44,7 @@ Our planning components are built based on the microautonomy architecture with A
 
 ## Component interface
 
-The following describes the input/output concept between Planning Component and other components. See the [Planning Component Interface (WIP)](../../autoware-interfaces/components/planning.md) page for the current implementation.
+This section describes the inputs and outputs of the Planning Component and of its internal modules. See the [Planning Component Interface](../../autoware-interfaces/components/planning.md) page for the current implementation.
 
 ### Input to the planning component