Adjust some documentation for threading intrinsics (#674)

* Synchronize `Binary.md` threading intrinsics

In #656 the threading-related intrinsics were revised and updated, but
`Binary.md` wasn't updated in the same PR. This commit removes the
removed intrinsics (`thread.switch-to` and `thread.yield-to`),
reorganizes the list slightly (moves `thread.yield` down), and then
renumbers the remaining intrinsics.

* Flag `thread.yield` under the async feature gate

This matches what wasm-tools/Wasmtime do at least which is
`thread.yield` is supported with just the component-model-async feature
and doesn't need component-model-threading. IIRC this is due to the fact
of this intrinsic existing prior to component-model-threading and it was
just renamed later on.

Author: alexcrichton

design/mvp/Binary.md

@@ -302,7 +302,6 @@ canon    ::= 0x00 0x00 f:<core:funcidx> opts:<opts> ft:<typeidx> => (canon lift
            | 0x05                                                => (canon task.cancel (core func)) 🔀
            | 0x0a v:<valtype> i:<u32>                            => (canon context.get v i (core func)) 🔀
            | 0x0b v:<valtype> i:<u32>                            => (canon context.set v i (core func)) 🔀
-           | 0x0c cancel?:<cancel?>                              => (canon thread.yield cancel? (core func)) 🔀
            | 0x06 async?:<async?>                                => (canon subtask.cancel async? (core func)) 🔀
            | 0x0d                                                => (canon subtask.drop (core func)) 🔀
            | 0x0e t:<typeidx>                                    => (canon stream.new t (core func)) 🔀
@@ -329,10 +328,13 @@ canon    ::= 0x00 0x00 f:<core:funcidx> opts:<opts> ft:<typeidx> => (canon lift
            | 0x23                                                => (canon waitable.join (core func)) 🔀
            | 0x26                                                => (canon thread.index (core func)) 🧵
            | 0x27 ft:<typeidx> tbl:<core:tableidx>               => (canon thread.new-indirect ft tbl (core func)) 🧵
-           | 0x28 cancel?:<cancel?>                              => (canon thread.switch-to cancel? (core func)) 🧵
+           | 0x28                                                => (canon thread.resume-later (core func)) 🧵
            | 0x29 cancel?:<cancel?>                              => (canon thread.suspend cancel? (core func)) 🧵
-           | 0x2a                                                => (canon thread.resume-later (core func)) 🧵
-           | 0x2b cancel?:<cancel?>                              => (canon thread.yield-to cancel? (core func)) 🧵
+           | 0x0c cancel?:<cancel?>                              => (canon thread.yield cancel? (core func)) 🔀
+           | 0x2a cancel?:<cancel?>                              => (canon thread.suspend-then-resume cancel? (core func)) 🧵
+           | 0x2b cancel?:<cancel?>                              => (canon thread.yield-then-resume cancel? (core func)) 🧵
+           | 0x2c cancel?:<cancel?>                              => (canon thread.suspend-then-promote cancel? (core func)) 🧵
+           | 0x2d cancel?:<cancel?>                              => (canon thread.yield-then-promote cancel? (core func)) 🧵
            | 0x40 shared?:<sh?> ft:<typeidx>                     => (canon thread.spawn-ref shared? ft (core func)) 🧵②
            | 0x41 shared?:<sh?> ft:<typeidx> tbl:<core:tableidx> => (canon thread.spawn-indirect shared? ft tbl (core func)) 🧵②
            | 0x42 shared?:<sh?>                                  => (canon thread.available-parallelism shared? (core func)) 🧵②

design/mvp/CanonicalABI.md

@@ -63,7 +63,7 @@ specified here.
   * [`canon thread.new-indirect`](#-canon-threadnew-indirect) 🧵
   * [`canon thread.resume-later`](#-canon-threadresume-later) 🧵
   * [`canon thread.suspend`](#-canon-threadsuspend) 🧵
-  * [`canon thread.yield`](#-canon-threadyield) 🧵
+  * [`canon thread.yield`](#-canon-threadyield) 🔀
   * [`canon thread.suspend-then-resume`](#-canon-threadsuspend-then-resume) 🧵
   * [`canon thread.yield-then-resume`](#-canon-threadyield-then-resume) 🧵
   * [`canon thread.suspend-then-promote`](#-canon-threadsuspend-then-promote) 🧵
@@ -4948,7 +4948,7 @@ cancellation, they can omit `cancellable` so that cancellation is instead
 delivered at a later `cancellable` call.
 
 
-### 🧵 `canon thread.yield`
+### 🔀 `canon thread.yield`
 
 For a canonical definition:
 ```wat