Update ping command docstrings and method return type hint.

[petyaslavova]

Pull Request check-list

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Description of change

Fixes #3714

[Copilot]

Pull Request Overview

Updates ping command documentation and type hints across Redis client classes to improve clarity and type safety. The changes standardize docstrings to clearly explain the ping functionality and fix return type annotations.

• Enhanced docstrings with detailed explanations of ping command purpose and usage
• Updated return type hints to be more specific (bool vs generic ResponseT, Awaitable[bool] vs generic Awaitable)
• Standardized documentation format across synchronous and asynchronous client implementations

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
redis/commands/core.py	Updated ping method return type hint and expanded docstring with detailed functionality description
redis/client.py	Enhanced ping method docstring with clearer description of functionality
redis/asyncio/client.py	Updated ping method return type hint and enhanced docstring to match synchronous version

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