Add Kiswahili translation (mmistakes#3489)

* Add Kiswahili translation

* Add Kiswahli to README

* Add Kiswahili to documentation

docs/_docs/08-ui-text.md

@@ -0,0 +1,54 @@
+---
+title: "UI Text"
+permalink: /docs/ui-text/
+excerpt: "Text for customizing user interface elements found in the theme."
+last_modified_at: 2021-05-11T10:22:55-04:00
+---
+
+Text for UI elements, `_layouts`, and `_includes` grouped together as a set of translation keys. This is by no means a full-on i18n solution, but it does help make customizing theme text a bit easier.
+
+The English[^yaml-anchors] main keys in [`_data/ui-text.yml`](https://github.com/mmistakes/minimal-mistakes/blob/master/_data/ui-text.yml) are translated in the following languages:
+
+- Arabic (عربي)
+- Brazilian Portuguese (Português brasileiro)
+- Catalan
+- Chinese
+- Danish
+- Dutch
+- Finnish
+- French (Français)
+- German (Deutsch)
+- Greek
+- Hebrew
+- Hungarian
+- Indonesian
+- Irish (Gaeilge)
+- Italian (Italiano)
+- Kiswahili
+- Korean
+- Japanese
+- Malayalam
+- Myanmar (Burmese)
+- Nepali (Nepalese)
+- Norwegian (Norsk)
+- Polish
+- Persian (فارسی)
+- Romanian
+- Russian
+- Slovak
+- Spanish (Español)
+- Swedish
+- Thai
+- Turkish (Türkçe)
+- Vietnamese
+
+If you're are interested in localizing them into other languages feel free to submit a pull request and I will be happy to look it over.
+
+[^yaml-anchors]: `en-US`, and `en-GB` use [YAML anchors](http://www.yaml.org/spec/1.2/spec.html#id2785586) to reference the values in `en` as to not repeat them.
+
+Many of the label based keys like `meta_label`, `categories_label`, `tags_label`, `share_on_label`, and `follow_label` can be left blank if you'd like to omit them from view. It really depends on you and if you want an even more minimal look to your site.
+
+![UI text labels]({{ "/assets/images/mm-ui-text-labels.jpg" | relative_url }})
+
+**Note:** The theme comes with localized text in English (`en`, `en-US`, `en-GB`). If you change `locale` in `_config.yml` to something else, most of the UI text will go blank. Be sure to add the corresponding locale key and translated text to `_data/ui-text.yml` to avoid this.
+{: .notice--warning}