Auto merge of #136272 - Zalathar:rollup-6s577l5, r=Zalathar

Rollup of 5 pull requests

Successful merges:

 - #135847 (optimize slice::ptr_rotate for small rotates)
 - #136215 (btree/node.rs: remove incorrect comment from pop_internal_level docs)
 - #136252 (spastorino back from vacations)
 - #136254 (Rustc dev guide subtree update)
 - #136259 (Cleanup docs for Allocator)

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

Author: bors