Suggestion to update documentation to use "::" instead of "0.0.0.0" for binding

**Issue description**
Currently, many documentation pages on grpc.io reference binding to 0.0.0.0, which explicitly limits the service to IPv4. This approach is increasingly outdated, as modern systems and best practices are shifting toward full IPv6 support.

To better align with current web standards and accommodate environments that are IPv6-only, the documentation should recommend using :: instead of 0.0.0.0 when binding to all interfaces. The :: address supports both IPv6 and dual-stack configurations (when supported by the platform), ensuring broader compatibility and future-proofing.

Additionally, referencing :: in the documentation helps promote IPv6 adoption by raising awareness. Many developers are still unfamiliar with IPv6 or are not actively considering it in their deployments. By using :: as the default example, the documentation can serve as a subtle but valuable educational tool, encouraging developers to think about modern networking requirements and nudging them toward more future-ready setups.