Add Urdu translations (#867)

### Prerequisites

Put an `x` into the box(es) that apply:

- [ ] This pull request fixes a bug.
- [x] This pull request adds a feature.
- [ ] This pull request introduces breaking change.

### Description

This commit adds urdu translations. 

Urdu uses the [Nastaliq](https://en.wikipedia.org/wiki/Nastaliq) script,
read from right to left. This script's unique style will often require
custom CSS. Because of these reasons, english text does not mix very
well with urdu. I felt it important to translate as much as possible
into Urdu for a better look and feel. For example, instead of 'Powered
By' in English, using the Urdu word for 'Thanks' was chosen as a
complete translation into Urdu might not work well due to differences in
subject-verb order

### Issues Resolved

List any existing issues this pull request resolves.

### Checklist

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#### General

- [x] Describe what changes are being made
- [x] Explain why and how the changes were necessary and implemented
respectively
- [ ] Reference issue with `#<ISSUE_NO>` if applicable

#### Resources

- [ ] If you have changed any SCSS code, run `make release` to
regenerate all CSS files

#### Contributors

- [x] Add yourself to `CONTRIBUTORS.md` if you aren't on it already

Co-authored-by: Muqeet Malik <muqeet.malik.-nd@disneystreaming.com>

docs/multilingual-mode.md

@@ -32,6 +32,7 @@ This theme supports the following languages:
 - Turkish
 - Simplified Chinese
 - Taiwan Chinese
+- Urdu
 
 ## Configure languages
 

i18n/ur.toml

@@ -0,0 +1,64 @@
+[categories]
+one = "قسم"
+other = "اقسام"
+
+[tags]
+one = "ٹیگ"
+other = "ٹیگز"
+
+[series]
+one = "سلسلہ"
+other = "سلسلہ"
+
+[authors]
+one = "مصنف"
+other = "مصنفین"
+
+[posts]
+other = "اِشاعَتی"
+
+[reading_time]
+one = "اسے پڑھنے میں ایک منٹ لگے گا"
+other = "اسے پڑھنے میں {{ Count }} منٹ لگتا ہے۔"
+
+[page_not_found]
+other = "صفحہ نہیں ملا"
+
+[page_does_not_exist]
+other = "معذرت، یہ صفحہ موجود نہیں ہے۔"
+
+[head_back]
+other = "آپ <a href=\"{{ . }}\">ہوم پیج</a> پر واپس جا سکتے ہیں۔"
+
+[licensed_under]
+other = "Licensed under"
+
+[powered_by]
+other = "شکریہ"
+
+[see_also]
+other = "بھی دیکھو"
+
+[note]
+other = "نوٹ"
+
+[tip]
+other = "ٹپ"
+
+[example]
+other = "مثال"
+
+[question]
+other = "سوال"
+
+[info]
+other = "معلومات"
+
+[warning]
+other = "انتباہ"
+
+[error]
+other = "غلطی"
+
+[link_to_heading]
+other = "Link to heading"