Add MP4 input limitation to Dynamic Camera Configuration user guide

[tdorauintc]

📝 Description

This PR updates the user guide for DLStreamer-Pipeline-Server (DLSPS) Pipeline Configuration:

• adds GStreamer limitation related to MP4 inputs support.
• adds a note to Troubleshooting section about checking DLSPS logs for errors.
• fixes duplicated section titles (in both pipeline configuration doc and in volume management doc).

✨ Type of Change

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• 🐞 Bug fix – Non-breaking change which fixes an issue
• 🚀 New feature – Non-breaking change which adds functionality
• 🔨 Refactor – Non-breaking change which refactors the code base
• 💥 Breaking change – Changes that break existing functionality
• 📚 Documentation update
• 🔒 Security update
• 🧪 Tests
• 🚂 CI

🧪 Testing Scenarios

Describe how the changes were tested and how reviewers can test them too:

• ✅ Tested manually
• 🤖 Ran automated end-to-end tests

✅ Checklist

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• 🔍 PR title is clear and descriptive
• 📝 For internal contributors: If applicable, include the JIRA ticket number (e.g., ITEP-123456) in the PR title. Do not include full URLs
• 💬 I have commented my code, especially in hard-to-understand areas
• 📄 I have made corresponding changes to the documentation
• ✅ I have added tests that prove my fix is effective or my feature works