Add mention of Vietnamese to UI text docs and update CHANGELOG/history

docs/_docs/08-ui-text.md

@@ -2,7 +2,7 @@
 title: "UI Text"
 permalink: /docs/ui-text/
 excerpt: "Text for customizing various user interface elements found in the theme."
-last_modified_at: 2017-07-07T15:08:15-04:00
+last_modified_at: 2017-08-06T10:30:33-04:00
 ---
 
 Text for various UI elements, `_layouts`, and `_includes` have all been grouped together as a set of translation keys. This is by no means a full-on i18n solution, but it does help make customizing things a bit easier.
@@ -23,6 +23,7 @@ Currently the English[^yaml-anchors] main keys in [`_data/ui-text.yml`](https://
 - Spanish (Español)
 - Swedish
 - 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.
 

docs/_docs/18-history.md

@@ -4,9 +4,15 @@ permalink: /docs/history/
 excerpt: "Change log of enhancements and bug fixes made to the theme."
 sidebar:
   nav: docs
-last_modified_at: 2017-08-04T12:32:47-04:00
+last_modified_at: 2017-08-06T10:31:32-04:00
 ---
 
+## Unreleased
+
+### Enhancements
+
+- Add Greek localized UI text strings. [#1159](https://github.com/mmistakes/minimal-mistakes/pull/1159)
+
 ## [4.5.0](https://github.com/mmistakes/minimal-mistakes/releases/tag/4.5.0)
 
 ### Enhancements