Update Urdu translation

[saadatm]

This PR updates the Urdu translation of Gulzar's website. Changes include:

• Editing and rewriting of almost the whole existing Urdu translation: correction of typos; more idiomatic translation of various phrases and terms; restructuring of sentences where appropriate, etc.
• Translation of the Engineering of Gulzar section
• Translation of figure captions

Will love it if my changes can be reviewed by somebody else too.

(Have some other suggestions/ideas regarding the markup & CSS as well; will create an issue to discuss them.)

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