This updates the VP8 payload diagrams to be compliant with RFC 7741. It also fixes some minor inconsistencies with PID, previously referred to as PartID. Bug: None Change-Id: I33eb57d96f3d95b01ef5f0afa21a9dc54b41db2d Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/230243 Reviewed-by: Danil Chapovalov <danilchap@webrtc.org> Commit-Queue: Emil Lundmark <lndmrk@webrtc.org> Cr-Commit-Position: refs/heads/main@{#34859}