help, README: link the topics, spell out the JSON documents and waiting

[karalabe]

• The README links ark help agents and each help topic to its source under src/help, so a reader on GitHub can open them without installing the tool.
• The output topic shows the stdout error document, a single error key around the code and message, with the real no-device example. It also names ark --json --version as the way to read the tool version that scripts should pin.
• The states topic says that status nests hardware (version, revision, model) and firmware (version, published), and that synced, paired and unlocked are null on firmware older than the tool supports.
• The agents topic says nothing in ark waits for an Ark to appear, so a script polls ark status --json, where no-device means none is attached yet.
• The root help's closing line and the README tell AI agents, not scripts, to read ark help agents first.
• Four topic source lines over 80 columns are reflowed with the words unchanged. The renderer wraps each source line on its own, so they printed raggedly.

Agents asked to write a script that waits for an Ark and prints its firmware version and lock state from --json all read the CLI's source or the published crate to find .error.code, .firmware.version and when unlocked is null, and most searched the help for a wait option that does not exist. Some also noted that the agents topic was only readable by running the binary.

Whether device-busy, device-unreachable and disconnected also mean "keep waiting" while an Ark is plugged in or boots needs checking on hardware first, so only no-device is named. datasets.md still has a colon elaboration ("snp-indel-calls first: the owner must upload"), left as written since the reflow keeps the words.