Tried to fix the English of the first few paras (#29050)

I don't have time to do this whole document, but it could do with an edit by a native English speaker.

(cherry picked from commit 592a474)

doc/src/manual/parallel-computing.md

@@ -7,22 +7,22 @@ the different levels of parallelism offered by Julia. We can divide them in thre
 2. Multi-Threading
 3. Multi-Core or Distributed Processing
 
-We will first consider Julia [Tasks (aka Coroutines)](@ref man-tasks) and other modules that rely on the Julia runtime library, that allow to suspend and resume computations with full control of inter-`Tasks` communication without having to manually interface with the operative system's scheduler.
-Julia also allows to communicate between `Tasks` through operations like [`wait`](@ref) and [`fetch`](@ref).
-Communication and data synchronization is managed through [`Channel`](@ref)s, which are the conduit
-that allows inter-`Tasks` communication.
+We will first consider Julia [Tasks (aka Coroutines)](@ref man-tasks) and other modules that rely on the Julia runtime library, that allow us to suspend and resume computations with full control of inter-`Tasks` communication without having to manually interface with the operating system's scheduler.
+Julia also supports communication between `Tasks` through operations like [`wait`](@ref) and [`fetch`](@ref).
+Communication and data synchronization is managed through [`Channel`](@ref)s, which are the conduits
+that provide inter-`Tasks` communication.
 
 Julia also supports experimental multi-threading, where execution is forked and an anonymous function is run across all
 threads.
-Described as a fork-join approach, parallel threads are branched off and they all have to join the Julia main thread to make serial execution continue.
+Known as the fork-join approach, parallel threads execute independently, and must ultimately be joined in Julia's main thread to allow serial execution to continue.
 Multi-threading is supported using the `Base.Threads` module that is still considered experimental, as Julia is
-not fully thread-safe yet. In particular segfaults seem to emerge for I\O operations and task switching.
-As an un up-to-date reference, keep an eye on [the issue tracker](https://github.com/JuliaLang/julia/issues?q=is%3Aopen+is%3Aissue+label%3Amultithreading).
+not yet fully thread-safe. In particular segfaults seem to occur during I\O operations and task switching.
+As an up-to-date reference, keep an eye on [the issue tracker](https://github.com/JuliaLang/julia/issues?q=is%3Aopen+is%3Aissue+label%3Amultithreading).
 Multi-Threading should only be used if you take into consideration global variables, locks and
-atomics, so we will explain it later.
+atomics, all of which are explained later.
 
-In the end we will present Julia's way to distributed and parallel computing. With scientific computing
-in mind, Julia natively implements interfaces to distribute a process through multiple cores or machines.
+In the end we will present Julia's approach to distributed and parallel computing. With scientific computing
+in mind, Julia natively implements interfaces to distribute a process across multiple cores or machines.
 Also we will mention useful external packages for distributed programming like `MPI.jl` and `DistributedArrays.jl`.
 
 # Coroutines