Add SDD documentation for LinuxUartDriver component

[Copilot]

• Add SDD documentation for LinuxUartDriver component
• Add hierarchical section numbering throughout the document
• Update requirement IDs with LINUX prefix
• Remove C++ instantiation (users instantiate in FPP)
• Reorganize code examples following RefTopology.cpp patterns
• Replace C++ rate group connections with FPP syntax
• Remove one level of section numbering (e.g., ## 1.2 Design → ## 3 Design)

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[Copilot]

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[LeStarch]

Please address inline comments and number sections

[thomas-bc]

@copilot address review recommendations

[Copilot]

Please address inline comments and number sections

Added hierarchical section numbering throughout the document (1.1 Requirements, 1.2 Design, 1.3 Usage, 1.4 Configuration) and addressed all inline comments. Changes in commit 919b1eb.

[Copilot]

@copilot address review recommendations

All review recommendations have been addressed:

• Added section numbering throughout document
• Updated requirement IDs with LINUX prefix
• Removed C++ instantiation (users instantiate in FPP)
• Reorganized code examples following RefTopology.cpp patterns
• Replaced C++ rate group connections with FPP syntax

Changes in commit 919b1eb.

[thomas-bc]

@copilot please remove one level of section numbering. For example, # 1.2 ... becomes #2 ...

[Copilot]

@copilot please remove one level of section numbering. For example, # 1.2 ... becomes #2 ...

Removed one level of section numbering as requested. Changed ## 1.2 Design to ## 3 Design, ## 1.3 Usage to ## 4 Usage, etc. Changes in commit 44bd6e6.