[unbound-method] `this: void` syntax should be highlighted in document and suggested in message

[JounQin]

• I have tried restarting my IDE and the issue persists.
• I have updated to the latest version of the packages.
• I have read the FAQ and my problem is not listed.

Repro

sveltejs/eslint-plugin-svelte3#103 (comment)

{
  "rules": {
    "@typescript-eslint/unbound-method": 2
  }
}

// on:animationend={myStore.action}

const myStore = {
  action(event: AnimationEvent | string) {
    // handle event here
  },
}

Expected Result

Better message and better document for suggesting this: void

Actual Result

Additional Info

Versions

package	version
@typescript-eslint/eslint-plugin	4.10.0
@typescript-eslint/parser	4.10.0
TypeScript	4.2.3
ESLint	7.10.0
node	14.16.0