Docs: Add references to Number collection convenience constructors

src/number.cr

@@ -71,6 +71,13 @@ struct Number
   # ints = Int64[1, 2, 3]
   # ints.class # => Array(Int64)
   # ```
+  #
+  # This is similar to an array literal of the same item type:
+  #
+  # ```
+  # Int64[1, 2, 3, 4]     # : Array(Int64)
+  # [1, 2, 3, 4] of Int64 # : Array(Int64)
+  # ```
   macro [](*nums)
     Array({{@type}}).build({{nums.size}}) do |%buffer|
       {% for num, i in nums %}
@@ -92,6 +99,14 @@ struct Number
   # ints = Int64.slice(1, 2, 3)
   # ints.class # => Slice(Int64)
   # ```
+  #
+  # This is a convenient alternative to `Slice.[]` for designating a
+  # specific item type which also considers autocasting.
+  #
+  # ```
+  # Int64.slice(1, 2, 3, 4)           # : Slice(Int64)
+  # Slice[1_i64, 2_i64, 3_i64, 4_i64] # : Slice(Int64)
+  # ```
   macro slice(*nums, read_only = false)
     %slice = Slice({{@type}}).new({{nums.size}}, read_only: {{read_only}})
     {% for num, i in nums %}
@@ -110,6 +125,14 @@ struct Number
   # ints = Int64.static_array(1, 2, 3)
   # ints.class # => StaticArray(Int64, 3)
   # ```
+  #
+  # This is a convenvenient alternative to `StaticArray.[]` for designating a
+  # specific item type which also considers autocasting.
+  #
+  # ```
+  # Int64.static_array(1, 2, 3, 4)          # : StaticArray(Int64)
+  # StaticArray[1_i64, 2_i64, 3_i64, 4_i64] # : StaticArray(Int64)
+  # ```
   macro static_array(*nums)
     %array = uninitialized StaticArray({{@type}}, {{nums.size}})
     {% for num, i in nums %}

src/slice.cr

@@ -29,7 +29,8 @@ struct Slice(T)
   # If `T` is a `Number` then this is equivalent to
   # `Number.slice` (numbers will be coerced to the type `T`)
   #
-  # See also: `Number.slice`.
+  # * `Number.slice` is a convenient alternative for designating a
+  #   specific numerical item type.
   macro [](*args, read_only = false)
     # TODO: there should be a better way to check this, probably
     # asking if @type was instantiated or if T is defined

src/static_array.cr

@@ -47,7 +47,8 @@ struct StaticArray(T, N)
   # ary.class # => StaticArray(Char | Int32, 2)
   # ```
   #
-  # See also: `Number.static_array`.
+  # * `Number.static_array` is a convenient alternative for designating a
+  #   specific numerical item type.
   macro [](*args)
     %array = uninitialized StaticArray(typeof({{*args}}), {{args.size}})
     {% for arg, i in args %}