application: transport_factory: update documented type of uavcan.serial.baudrate

[coderkalyan]

Fixes #168

[coveralls]

Pull Request Test Coverage Report for Build 40066989

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.07%) to 95.758%

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Totals
Change from base Build 39062615:	0.07%
Covered Lines:	13416
Relevant Lines:	13855

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💛 - Coveralls

[coderkalyan]

@pavel-kirienko done.