docs(echo): drop the duplicated on-chain paragraphs

The signer discovery note is true of every example, so it belongs in the
repo README, not here. The closing contrast restated what this section
and tiles already say about metered vs fixed.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: rickstaa

echo/README.md

@@ -92,14 +92,10 @@ uv run client.py sample.mp4 --mode blur \
 docker compose -f compose.yml -f compose.onchain.yml down
 ```
 
-Both flags are here because the demo signer runs without `-remoteDiscovery`. A signer started with that flag serves `/discover-orchestrators` itself, and the SDK falls back to it whenever no discovery URL is given (here that takes `--discovery ''`, since the flag defaults to the local orchestrator).
-
 The ffmpeg and webcam pipes above work the same way on-chain: add `--signer` to the `client.py` in the pipeline. Without it the client stops at the payment challenge (`Live runner paid call requires signer_url`), which closes the pipe and leaves ffmpeg reporting `Broken pipe` — the paid stack refusing an unpaid caller, not a broken camera.
 
 A metered session pays **more than once**. The upfront payment that answers the 402 challenge only buys the signer's preroll (about ten seconds), while the orchestrator keeps debiting every few seconds and releases the session on the first debit it cannot cover. So `reserve_session` keeps the session funded in the background for as long as the client holds it, and leaving the client's `async with session` block stops that before the session is released. A stream that outlives the preroll is the whole point of this example on-chain, so use a clip of at least a few tens of seconds (the 30s `sample.mp4` above is enough): watch `docker compose logs -f orchestrator` and you should see repeated payments, not one.
 
-That is the difference from `hello-world` and `tiles`, whose fixed pricing settles the entire bill upfront and starts no ticker.
-
 ## Run without Docker
 
 Start an orchestrator built from go-livepeer `v0.9.0` or newer (see [Build from source](https://docs.livepeer.org/v1/orchestrators/guides/install-go-livepeer#build-from-source)), then the app and client directly: