Verify v2.4.0 features are documented

[shaloo]

https://agno-agi.slack.com/archives/C0912M8NJR0/p1768289560586659

[shaloo]

May also have Agent Builder via (@ysolanky https://agno-agi.slack.com/archives/C0912M8NJR0/p1768307679380839?thread_ts=1768289560.586659&cid=C0912M8NJR0 - verify docs are in place / updated.

[shaloo]

v2.4.0 Release Note (highlight this for user?)

1. Custom Headers (GET support only), POST in the works (Ref: https://agno-agi.slack.com/archives/C0912M8NJR0/p1768307764627019?thread_ts=1768306552.404869&cid=C0912M8NJR0), also see [Bug] Custom Headers in OS Setting only work for GET Request agno#5952 . Afaict, this is just a FE thing (not implemented), backend APIs may be there though I cannot put a finger in the reference section yet where this is listed. Need to talk to somone in the know. @kausmeows who can help me figure out this is correct - no doc update needed for this (current assessment).

• [ x ] Check if A2A client task cancel not supported is accurate via Mustafa.
• [ x ] linear tracking issue #430

In that case we may need to update https://docs.agno.com/agent-os/interfaces/a2a/introduction#a2a