chore: fix typos in comment
## Fix Typos in Comments
This PR addresses several typos in the Rust standard library's documentation comments:
- In `library/std/src/sync/mpmc/list.rs`: Corrected "attemped" to "attempted"
- In `library/std/src/sys/thread_local/guard/key.rs`: Fixed "defering" to "deferring"
- In `library/std/src/sys/thread_local/guard/key.rs`: Fixed "futher" to "further"
These changes improve documentation readability and consistency without affecting any functional code.