fix: warning for relative links

[isamu-takagi]

Description

Fix a warning for relative links when generating documentation. Below are some of the warnings.

$ mike deploy HEAD
...
INFO    -  Doc file 'how-to-guides/integrating-autoware/creating-vehicle-and-sensor-model/calibrating-sensors/lidar-lidar-calibration/index.md' contains an unrecognized relative link
           '../extrinsic-manual-calibration', it was left as is. Did you mean '../extrinsic-manual-calibration/index.md'?
INFO    -  Doc file 'how-to-guides/integrating-autoware/creating-vehicle-and-sensor-model/calibrating-sensors/lidar-lidar-calibration/index.md' contains an unrecognized relative link
           '../extrinsic-manual-calibration', it was left as is. Did you mean '../extrinsic-manual-calibration/index.md'?
INFO    -  Doc file 'how-to-guides/integrating-autoware/creating-vehicle-and-sensor-model/creating-sensor-model/index.md' contains an unrecognized relative link '../calibrating-sensors', it
           was left as is. Did you mean '../calibrating-sensors/index.md'?
WARNING -  Doc file 'how-to-guides/integrating-autoware/creating-vehicle-and-sensor-model/creating-vehicle-model/index.md' contains a relative link
           '../../creating-vehicle-interface-package/creating-a-vehicle-interface-for-an-ackermann-kinematic-model.md', but the target
           'how-to-guides/integrating-autoware/creating-vehicle-interface-package/creating-a-vehicle-interface-for-an-ackermann-kinematic-model.md' is not found among documentation files.
...

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[ismetatabay]

I have tested it, and this pull request resolves the warnings. Thank you.
LGTM