Update documentation for language recognition

[sahilsuman933]

Description

• Corrected Gladia's multilingual support to accurately reflect its automatic language detection and code-switching capabilities.
• Updated Gladia's supported language count from 80+ to 90+ across the documentation.
• Integrated Gladia into multilingual configuration steps, performance notes, and troubleshooting sections.

Testing Steps

• Run the app locally using fern docs dev or navigate to preview deployment
• Ensure that the changed pages and code snippets work

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