Add comprehensive README documentation for bondmachine command

[Copilot]

The bondmachine command lacked user-facing documentation. Added comprehensive README.md covering all functionality.

Documentation Structure

• Installation and Overview: Quick start and command purpose
• Core Features (100+ flags organized by category):
  • Machine construction (domains, processors, I/O, bonds, shared objects)
  • Simulation and emulation modes
  • Verilog/HDL generation with board-specific support (Basys3, iCE40 variants)
  • Peripheral integration (VGA, PS2, UART, counters)
  • Clustering protocols (Etherbond, UDPBond, Bondirect)
  • BMAPI generation for Go/C/Python
• Usage Examples: Common workflows from machine creation to FPGA deployment
• Reference: File formats, architecture flow, tips, related commands

Follows existing documentation patterns from cmd/simbox and cmd/bmnumbers for consistency.

Original prompt

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This section details on the original issue you should resolve

<issue_title>bondmachine command readme</issue_title>
<issue_description>Write a README.md file with the documentation for the bondmachine command. The file should be in cmd/bondmachine/</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes bondmachine command readme #45

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