[docs] d78b44a further broke `default` cell of `releasedLabels` in `Options` table

[BinToss]

It didn't work well before and it got worse after.
https://github.com/semantic-release/github/blame/d78b44ab2d2e1b14ea9368892a278313beaed89e/README.md#L90

before:

Option	Description	Default
releasedLabels	The labels to add to each issue and pull request resolved by the release. Set to false to not add any label. See releasedLabels.	['released<%= nextRelease.channel ? \ on @${nextRelease.channel}` : "" %>']`

after:

Option	Description	Default
releasedLabels	The labels to add to each issue and pull request resolved by the release. Set to false to not add any label. See releasedLabels.	['released<%= nextRelease.channel ? \ on @${nextRelease.channel}` : "" %>']-

---

The following is closer to what I think is correct, but may need review by someone who can verify the code snippet is correct..

Option	Description	Default
releasedLabels	The labels to add to each issue and pull request resolved by the release. Set to false to not add any label. See releasedLabels.	['released<%= nextRelease.channel ? \` on @\${nextRelease.channel}\` : "" %>']

| Option | Description | Default |
| --- | --- | --- |
| `releasedLabels`      | The [labels](https://help.github.com/articles/about-labels) to add to each issue and pull request resolved by the release. Set to `false` to not add any label. See [releasedLabels](#releasedlabels). | ```['released<%= nextRelease.channel ? \` on @\${nextRelease.channel}\` : "" %>']``` |

Although a <pre lang="js"> tag could be used to give Javascript code highlighting, doing so makes the entire Default column very wide. I see why that wasn't done before.

For reference, here's the code block with Javascript highlighting.

['released<%= nextRelease.channel ? \` on @\${nextRelease.channel}\` : "" %>']