fix: Fix typos in Russian translation for staking page

[Sshadow84]

Description

This PR fixes several typos and issues in the Russian translation for the staking page.

Changes:

• Fixed typo: "Основная сетьu" → "Основная сеть" (extra letter "u")
• Translated untranslated string: "More on staking withdrawals" → "Подробнее о выводе средств из стейкинга"
• Fixed Ukrainian letters used instead of Russian: "фінансовій" → "финансовый"
• Fixed Ukrainian letters used instead of Russian: "Самостоятельній" → "Самостоятельный"

Type of change

• Translation/content update

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