Squeeze the last bits of `task`s in documentation in favor of `thread`
An automated script was run against the `.rs` and `.md` files,
subsituting every occurrence of `task` with `thread`. In the `.rs`
files, only the texts in the comment blocks were affected.
@@ -3635,7 +3635,7 @@ that have since been removed):
* ML Kit, Cyclone: region based memory management
* Haskell (GHC): typeclasses, type families
* Newsqueak, Alef, Limbo: channels, concurrency
-* Erlang: message passing, task failure, ~~linked task failure~~,
+* Erlang: message passing, thread failure, ~~linked thread failure~~,
~~lightweight concurrency~~
* Swift: optional bindings
* Scheme: hygienic macros
