Enhancement Request: Add Icelandic HTML Entities to `unescapingTable`

### Enhancement Request: Add Icelandic HTML Entities to `unescapingTable`

**Description:**
I would like to request the addition of Icelandic HTML entities to the `unescapingTable` in the HTML string mappings. Specifically, it would be beneficial to include the following entities:

- `Þ` for `Þ`
- `þ` for `þ`
- `ú` for `ú`
- `é` for `é`

**Rationale:**
Icelandic texts often contain these characters, and their inclusion in the `unescapingTable` would enhance text processing by allowing accurate decoding of HTML-encoded Icelandic strings. This would improve the usability and accuracy of the library when handling Icelandic content.

**Proposed Solution:**
Update the `unescapingTable` to include the mappings for these Icelandic entities. Here is an example of the proposed additions:

**Additional Information:**
These updates align with the existing functionality of the library and provide better support for Icelandic language text processing.

Thank you for considering this enhancement. I appreciate the effort in maintaining and improving this project.

Kind regards