docs: update honcho CLI reference + document plugin CLI registration (#5308)
Post PR #5295 docs audit — 4 fixes:
1. cli-commands.md: Update hermes honcho subcommand table with 4
missing commands (peers, enable, disable, sync), --target-profile
flag, --all on status, correct mode values (hybrid/context/tools
not hybrid/honcho/local), and note that setup redirects to
hermes memory setup.
2. build-a-hermes-plugin.md: Replace 'ctx.register_command() —
planned but not yet implemented' with the actual implemented
ctx.register_cli_command() API. Add full Register CLI commands
section with code example.
3. memory-provider-plugin.md: Add 'Adding CLI Commands' section
documenting the register_cli(subparser) convention for memory
provider plugins, active-provider gating, and directory structure.
4. plugins.md: Add CLI command registration to the capabilities table.