docs(redecryptor): Clarify that we're talking about the UI timeline in the graph

Author: poljar

crates/matrix-sdk/src/event_cache/redecryptor.rs

@@ -46,6 +46,10 @@
 //! received and R2D2 won't get notified about it. To work around this
 //! decryption requests can be explicitly sent to R2D2.
 //!
+//! In the graph bellow the Timeline block is meant to be the `Timeline` from
+//! the `matrix-sdk-ui` crate, but it could be any other listener that
+//! subscribes to [`RedecryptorReport`] stream.
+//!
 //! ```markdown
 //! 
 //!      .----------------------.