Update dependency typedoc-plugin-markdown to v4.2.7 (#954)

This PR contains the following updates:

| Package | Change | Age | Adoption | Passing | Confidence |
|---|---|---|---|---|---|
| [typedoc-plugin-markdown](https://typedoc-plugin-markdown.org)
([source](https://redirect.github.com/typedoc2md/typedoc-plugin-markdown/tree/HEAD/packages/typedoc-plugin-markdown))
| [`4.2.6` ->
`4.2.7`](https://renovatebot.com/diffs/npm/typedoc-plugin-markdown/4.2.6/4.2.7)
|
[![age](https://developer.mend.io/api/mc/badges/age/npm/typedoc-plugin-markdown/4.2.7?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![adoption](https://developer.mend.io/api/mc/badges/adoption/npm/typedoc-plugin-markdown/4.2.7?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![passing](https://developer.mend.io/api/mc/badges/compatibility/npm/typedoc-plugin-markdown/4.2.6/4.2.7?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|
[![confidence](https://developer.mend.io/api/mc/badges/confidence/npm/typedoc-plugin-markdown/4.2.6/4.2.7?slim=true)](https://docs.renovatebot.com/merge-confidence/)
|

---

### Release Notes

<details>
<summary>typedoc2md/typedoc-plugin-markdown
(typedoc-plugin-markdown)</summary>

###
[`v4.2.7`](https://redirect.github.com/typedoc2md/typedoc-plugin-markdown/blob/HEAD/packages/typedoc-plugin-markdown/CHANGELOG.md#427)

[Compare
Source](https://redirect.github.com/typedoc2md/typedoc-plugin-markdown/compare/typedoc-plugin-markdown@4.2.6...42079ce4068bc8a83fcf4309004f7ff76358e592)

##### Patch Changes

- Correctly handle top level custom groups in navigation
([#&#8203;685](https://redirect.github.com/typedoc2md/typedoc-plugin-markdown/issues/685))
- Fix missing index descriptions for some signatures
([#&#8203;670](https://redirect.github.com/typedoc2md/typedoc-plugin-markdown/issues/670))
-   Add '?' for optional type declarations in tables

</details>

---

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