Add Polish localized UI text strings

Ref: #1304

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: 2017-08-18T12:27:07-04:00
+last_modified_at: 2017-10-16T12:41:11-04:00
 ---
 
 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.
@@ -20,6 +20,7 @@ Currently the English[^yaml-anchors] main keys in [`_data/ui-text.yml`](https://
 - Italian (Italiano)
 - Korean
 - Nepali (Nepalese)
+- Polish
 - Russian
 - Spanish (Español)
 - Swedish

docs/_docs/18-history.md

@@ -4,7 +4,7 @@ permalink: /docs/history/
 excerpt: "Change log of enhancements and bug fixes made to the theme."
 sidebar:
   nav: docs
-last_modified_at: 2017-10-04T16:33:00-04:00
+last_modified_at: 2017-10-16T12:40:54-04:00
 ---
 
 ## Unreleased
@@ -19,6 +19,7 @@ last_modified_at: 2017-10-04T16:33:00-04:00
 - Improve accessibility of navigation menu button. [#1099](https://github.com/mmistakes/minimal-mistakes/issues/1099)
 - Add Naver Webmaster Tools verification. [#1286](https://github.com/mmistakes/minimal-mistakes/pull/1286)
 - Add support for Staticman v2 endpoint and reCAPTCHA.
+- Add Polish localized UI text strings. [#1304](https://github.com/mmistakes/minimal-mistakes/pull/1304)
 
 ### Bug Fixes