tweak some wording

Author: IanButterworth

doc/src/manual/multi-threading.md

@@ -301,12 +301,12 @@ julia> sum_multi_good(1:1_000_000)
 500000500000
 ```
 
-Note that we do not use buffers based on the `threadid()` i.e. `buffers = zeros(Threads.nthreads())` because tasks can
-actually change thread at yield points, known as task migration (docs??), which would introduce data races for such a
-buffering approach.
+Note buffers should not be managed based on the `threadid()` i.e. `buffers = zeros(Threads.nthreads())` because tasks can
+actually change thread at yield points, known as [task migration](@ref man-task-migration), which introduces potential for
+data races for such a buffering approach.
 
-Another option, which would not be performant for a naive sum like this, is the use of atomic operations on variables shared
-across all threads.
+Another option is the use of atomic operations on variables shared across tasks/threads, which may be more performant
+depending on the characteristics of the operations.
 
 ## Atomic Operations