Update README.md to add Slovenian (Slovenščina) (sl_SI) (#2735)

# Description

Please provide a summary of the changes, including relevant motivation
and context.

Closes #(issue_number)

## Checklist

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have performed a self-review of my own code
- [ ] I have attached images of the change if it is UI based
- [ ] I have commented my code, particularly in hard-to-understand areas
- [ ] If my code has heavily changed functionality I have updated
relevant docs on [Stirling-PDFs doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
- [ ] My changes generate no new warnings
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

README.md

@@ -113,7 +113,7 @@ Visit our comprehensive documentation at [docs.stirlingpdf.com](https://docs.sti
 
 ## Supported Languages
 
-Stirling-PDF currently supports 38 languages!
+Stirling-PDF currently supports 39 languages!
 
 | Language                                     | Progress                               |
 | -------------------------------------------- | -------------------------------------- |
@@ -148,6 +148,7 @@ Stirling-PDF currently supports 38 languages!
 | Serbian Latin alphabet (Srpski) (sr_LATN_RS) | ![64%](https://geps.dev/progress/64)   |
 | Simplified Chinese (简体中文) (zh_CN)         | ![90%](https://geps.dev/progress/90)   |
 | Slovakian (Slovensky) (sk_SK)                | ![75%](https://geps.dev/progress/75)   |
+| Slovenian (Slovenščina) (sl_SI)              | ![94%](https://geps.dev/progress/75)   |
 | Spanish (Español) (es_ES)                    | ![88%](https://geps.dev/progress/88)   |
 | Swedish (Svenska) (sv_SE)                    | ![88%](https://geps.dev/progress/88)   |
 | Thai (ไทย) (th_TH)                           | ![87%](https://geps.dev/progress/87)   |

scripts/ignore_translation.toml

@@ -211,7 +211,7 @@ ignore = [
     'watermark.type.1',
 ]
 
-[si_SL]
+[sl_SI]
 ignore = [
     'language.direction',
 ]