[Task]:Docs: clarify Python 3.10 requirement on Ubuntu 24.04 and Codespaces

[renu-123-pixel]

What needs to happen?

What changed

This PR documents an issue encountered when building Apache Beam on
Ubuntu 24.04 and GitHub Codespaces where the python3.10 command is not
available by default.

It adds guidance explaining the error and provides a simple workaround
using a symbolic link to the installed Python version.

Why

New contributors using Ubuntu 24.04 or Codespaces frequently encounter
build failures during Python SDK setup. This documentation update helps
avoid confusion and reduces onboarding friction.

Testing

Documentation-only change.

Issue Priority

Priority: 2 (default / most normal work should be filed as P2)

Issue Components

• Component: Python SDK
• Component: Java SDK
• Component: Go SDK
• Component: Typescript SDK
• Component: IO connector
• Component: Beam YAML
• Component: Beam examples
• Component: Beam playground
• Component: Beam katas
• Component: Website
• Component: Infrastructure
• Component: Spark Runner
• Component: Flink Runner
• Component: Samza Runner
• Component: Twister2 Runner
• Component: Hazelcast Jet Runner
• Component: Google Cloud Dataflow Runner

[PDGGK]

Hi, I'd like to work on this issue.

I can add documentation to CONTRIBUTING.md clarifying the Python 3.10 requirement on Ubuntu 24.04 and Codespaces, including the symlink workaround for when python3.10 command is not available by default.

.take-issue