Chore: Update SMS OTP messaging and FAQ for clarity

[lohanidamodar]

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Summary by CodeRabbit

• Documentation
  • Updated SMS/OTP pricing model to clarify per-message billing.
  • Added guidance on using mock phone numbers for testing without incurring costs.
  • Introduced country-by-country rate pricing table.
  • Updated FAQ content to reflect current billing approach.

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[coderabbitai]

Walkthrough

Three documentation files were updated to reflect changes to the phone OTP and SMS pricing model. The primary modifications include renaming documentation sections from "Free messages" to "Free testing," removing references to 10 free monthly SMS messages, and updating billing terminology to clarify per-message charges. A reference to mock phone numbers for testing was added, and mentions of country-based rates were included. The changes maintain consistency across advanced platform documentation, product authentication docs, and FAQ content.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main changes: updates to SMS OTP messaging across documentation and FAQ for improved clarity.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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