Apply suggestions from code review

Co-authored-by: Milan Bouchet-Valat <nalimilan@club.fr>

Author: tkf

base/multidimensional.jl

@@ -1568,11 +1568,11 @@ end
 """
     extrema([f,] A::AbstractArray; dims, [init]) -> Array{Tuple}
 
-Compute the minimum and maximum of `f` applied to each element (if given) in the given
-dimensions of `A`.
+Compute the minimum and maximum elements of `A` over dimensions `dims`.
+If `f` is provided, return the minimum and maximum elements after applying `f` to them.
 
 !!! compat "Julia 1.2"
-    2-argument `extrema` method requires Julia 1.2 or later.
+    The `extrema(f, A)` method requires Julia 1.2 or later.
 
 # Examples
 ```jldoctest

base/reduce.jl

@@ -768,8 +768,8 @@ minimum(a; kw...) = mapreduce(identity, min, a; kw...)
 Compute both the minimum and maximum element in a single pass, and return them as a 2-tuple.
 
 The value returned for empty `itr` can be specified by `init`. It must be a 2-tuple whose
-first/second element is a neutral element for `min`/`max` (i.e. which is greater/less than
-or equal to any other element). This is required because it is unspecified whether `init`
+first and second elements are neutral elements for `min` and `max` respectively
+(i.e. which are greater/less than or equal to any other element).
 is used for non-empty collections. Note: it implies that, for empty `itr`, the first
 element is typically _greater_ than the last element. This is a "paradoxical" but yet
 expected result.
@@ -798,8 +798,8 @@ Compute both the minimum and maximum of `f` applied to each element in `itr` and
 them as a 2-tuple. Only one pass is made over `itr`.
 
 The value returned for empty `itr` can be specified by `init`. It must be a 2-tuple whose
-first/second element is a neutral element for `min`/`max` (i.e. which is greater/less than
-or equal to any other element). This is required because it is unspecified whether `init`
+first and second elements are neutral elements for `min` and `max` respectively
+(i.e. which are greater/less than or equal to any other element).
 is used for non-empty collections. Note: it implies that, for empty `itr`, the first
 element is typically _greater_ than the last element. This is a "paradoxical" but yet
 expected result.