add sticky task warning to @task and schedule (#54815)

The fact that `@async` causes the task that it was scheduled from to
also become sticky is well documented in the warning in [`@async`
docs](https://docs.julialang.org/en/v1/base/parallel/#Base.@async), but
it's not clear that creating a task and scheduling it also has the same
effect, by default.

Author: IanButterworth

base/docs/basedocs.jl

@@ -1766,7 +1766,8 @@ The task will run in the "world age" from the parent at construction when [`sche
 !!! warning
     By default tasks will have the sticky bit set to true `t.sticky`. This models the
     historic default for [`@async`](@ref). Sticky tasks can only be run on the worker thread
-    they are first scheduled on. To obtain the behavior of [`Threads.@spawn`](@ref) set the sticky
+    they are first scheduled on, and when scheduled will make the task that they were scheduled
+    from sticky. To obtain the behavior of [`Threads.@spawn`](@ref) set the sticky
     bit manually to `false`.
 
 # Examples

base/task.jl

@@ -115,6 +115,13 @@ end
 Wrap an expression in a [`Task`](@ref) without executing it, and return the [`Task`](@ref). This only
 creates a task, and does not run it.
 
+!!! warning
+    By default tasks will have the sticky bit set to true `t.sticky`. This models the
+    historic default for [`@async`](@ref). Sticky tasks can only be run on the worker thread
+    they are first scheduled on, and when scheduled will make the task that they were scheduled
+    from sticky. To obtain the behavior of [`Threads.@spawn`](@ref) set the sticky
+    bit manually to `false`.
+
 # Examples
 ```jldoctest
 julia> a1() = sum(i for i in 1:1000);
@@ -839,6 +846,13 @@ the woken task.
     It is incorrect to use `schedule` on an arbitrary `Task` that has already been started.
     See [the API reference](@ref low-level-schedule-wait) for more information.
 
+!!! warning
+    By default tasks will have the sticky bit set to true `t.sticky`. This models the
+    historic default for [`@async`](@ref). Sticky tasks can only be run on the worker thread
+    they are first scheduled on, and when scheduled will make the task that they were scheduled
+    from sticky. To obtain the behavior of [`Threads.@spawn`](@ref) set the sticky
+    bit manually to `false`.
+
 # Examples
 ```jldoctest
 julia> a5() = sum(i for i in 1:1000);