Auto merge of rust-lang#94648 - RalfJung:rollup-4iorcrd, r=RalfJung

Rollup of 4 pull requests

Successful merges:

 - rust-lang#94630 (Update note about tier 2 docs.)
 - rust-lang#94633 (Suggest removing a semicolon after derive attributes)
 - rust-lang#94642 (Fix source code pages scroll)
 - rust-lang#94645 (do not attempt to open cgroup files under Miri)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

std/src/sys/unix/thread.rs

@@ -384,6 +384,11 @@ fn cgroup2_quota() -> usize {
     use crate::path::PathBuf;
 
     let mut quota = usize::MAX;
+    if cfg!(miri) {
+        // Attempting to open a file fails under default flags due to isolation.
+        // And Miri does not have parallelism anyway.
+        return quota;
+    }
 
     let _: Option<()> = try {
         let mut buf = Vec::with_capacity(128);