Preserve formatting over range (mermaid diagrams)

[nuke-web3]

https://prettier.io/docs/en/ignore#range-ignore

Example:

<!-- prettier-ignore-start -->
<diagram class="mermaid">
  flowchart LR
  subgraph paraA[Parachain A]
    palletxcma("pallet-xcm") --"1. execute"--> executora("xcm-executor")
    executora --"send"--> sendera("xcm-sender")
  end

  subgraph tdestination[Trusted Destination]
  end
  lteleport("limited_teleport_assets(\n  dest,\n  beneficiary,\n  assets,\n  fee_asset_item,\n  weight_limit\n)"):::left --> palletxcma

  sendera --"2."--> tdestination

  classDef left text-align:left
</diagram>
<!-- prettier-ignore-end -->

Want to do this throughout, as prettier now clobbers the indents when there is a \n\n encountered 🙃

[nuke-web3]

need to update the contributor guide for this.