Review and update EasyCLA documentation for FinAI training

[mlehotskylf]

Description

Review and update the EasyCLA documentation at https://docs.linuxfoundation.org/lfx/easycla to ensure it is accurate, complete, and up-to-date.

This documentation will be used to train FinAI (the Intercom AI assistant), so it needs to be a reliable source of truth for answering user questions about EasyCLA.

Tasks

• Review all pages under https://docs.linuxfoundation.org/lfx/easycla for accuracy
• Identify outdated content, or missing information
• Update documentation to reflect current EasyCLA behavior and UI
• Ensure coverage of common user workflows and FAQs
• Verify that the documentation is clear enough for AI consumption (structured, unambiguous)

Context

Parent: #4938

This is part of the Intercom integration effort. FinAI will use this documentation as its knowledge base to provide automated support to EasyCLA users.