Update noteworthy-differences.md (#54939)

Additional comparison with Matlab for bulk editing matrices for
operations such as applying a threshold.

Useful discussion here:

https://discourse.julialang.org/t/replacing-values-of-specific-entries-in-an-array-in-julia/25259

and here:

https://stackoverflow.com/questions/56583807/replacing-values-of-specific-entries-in-an-array-in-julia

Author: igrqb

doc/src/manual/noteworthy-differences.md

@@ -82,6 +82,9 @@ may trip up Julia users accustomed to MATLAB:
     provides the higher order functions [`filter`](@ref) and [`filter!`](@ref), allowing users
     to write `filter(z->z>3, x)` and `filter!(z->z>3, x)` as alternatives to the corresponding transliterations
     `x[x.>3]` and `x = x[x.>3]`. Using [`filter!`](@ref) reduces the use of temporary arrays.
+  * Following on from the previous point, to replace values that meet specific criteria, for example a
+    thresholding operation on all elements in a matrix, could be achieved in Matlab as follows `A(A < threshold) = 0`.
+    The Julia equivalent would be `A[A .< threshold] .= 0`.
   * The analogue of extracting (or "dereferencing") all elements of a cell array, e.g. in `vertcat(A{:})`
     in MATLAB, is written using the splat operator in Julia, e.g. as `vcat(A...)`.
   * In Julia, the `adjoint` function performs conjugate transposition; in MATLAB, `adjoint` provides the