# Description

This PR changes a few things:
* `--dev` flag will not conflict with `--chain` anymore, but if
`--chain` is not given will set `--chain=dev`.
* `--dev-block-time` is optional and it defaults to 3000ms if not set
after setting `--dev`.
* to start OmniNode with manual seal it is enough to pass just `--dev`.
* `--dev-block-time` can still be used to start a node with manual seal,
but it will not set it up as `--dev` does (it will not set a bunch of
flags which are enabled by default when `--dev` is set: e.g. `--tmp`,
`--alice` and `--force-authoring`.

Closes: #6537

## Integration

Relevant for node/runtime developers that use OmniNode lib, including
`polkadot-omni-node` binary, although the recommended way for runtime
development is to use `chopsticks`.

## Review Notes

* Decided to focus only on OmniNode & templates docs in relation to it,
and leave the `parachain-template-node` as is (meaning `--dev` isn't
usable and te...