feat: custom head title (#950)

### Prerequisites

Put an `x` into the box(es) that apply:

- [ ] This pull request fixes a bug.
- [x] This pull request adds a feature.
- [ ] This pull request introduces breaking change.

### Description

This PR makes it possible to configure a custom head title, without
having to override the baseof template.

### Issues Resolved

https://github.com/luizdepra/hugo-coder/issues/811

### Checklist

Put an `x` into the box(es) that apply:

#### General

- [ ] Describe what changes are being made
- [ ] Explain why and how the changes were necessary and implemented
respectively
- [ ] Reference issue with `#<ISSUE_NO>` if applicable

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Co-authored-by: Luiz F. A. de Prá <luizdepra@users.noreply.github.com>