Key developments: PR merged for 1.90 update of the FLS. We're preparing now to work on the 1.91 update of the FLS.
Blockers: None currently
Help wanted: Anyone that's familiar with the Rust Reference is more than encouraged to read through the FLS to get a sense of it and where further alignment may be possible. Feel free to open issues on the FLS repo as you find things.
We're putting together a prototype/demo of our reference changes at https://rust-lang.github.io/project-goal-reference-expansion/ . This includes a demonstration of tooling changes to provide stability markers (both "documenting unstable Rust" and "unstable documentation of stable Rust").
The work on this goal has led to many ongoing discussions on the current status of the Reference. Those discussions are still in progress.
Meanwhile, many people working on this goal have successfully written outlines or draft chapters, at various stages of completeness. There's a broken-out status report at https://github.com/rust-lang/project-goal-reference-expansion/issues/11 .