This pull request makes significant updates to the documentation to reflect major changes in ROCmRoll's channel management, GPU detection, and profile handling. The main improvements include replacing the old per-GPU-family RDNA1/RDNA2 channels with a new multi-architecture (multi-arch) approach, introducing automatic channel switching based on GPU support, and enhancing profile management commands. These changes clarify how ROCmRoll resolves the correct install channel and packages for each GPU, streamline the user experience, and update troubleshooting guidance.

Channel and Install Source Changes

• Replaced the old rdna1 and rdna2 channels with new legacy and legacy-staging channels, and updated all documentation to use the new multi-arch channels (preview, nightly) for RDNA1/2 support. The multi-arch channels use exact GPU chip IDs for package selection, improving compatibility and future-proofing installs. [1] [2] [3] [4]
• Documented automatic channel switching: if a GPU family is not supported by a channel (e.g., stable for RDNA1/2, or multi-arch for MI300/MI350), ROCmRoll transparently selects the appropriate fallback channel. [1] [2] [3]

GPU Detection and Exact Chip Resolution

• Added detailed explanations of how ROCmRoll detects both the GPU family and the exact chip, and how these are used to select the correct install source and packages for each channel type. This includes updates to describe the new multiArchChip field in environment state and its use in caching and launcher generation. [1] [2]

Profile Management Enhancements

• Expanded documentation for profile commands, including new profiles, the profile apply command, and its integration with ComfyUI Desktop entries. Updated the options table and usage examples accordingly. [1] [2] [3] [4]

Troubleshooting and Migration Guidance

• Updated troubleshooting instructions to reflect the new automatic channel switching and migration from the removed rdna1/rdna2 channels to preview, with clear guidance for users of older installations.
• Added documentation about channel aliases and how instance state migration works to ensure backward compatibility. [1] [2]

Other Documentation Updates

• Clarified the differences between install sources (directUrls, index, multiArch), cache locations, and the impact of these changes on the install and repair process. [1] [2]

These changes modernize and clarify ROCmRoll's documentation to match its improved architecture and user experience.