doc: add compat for mktemp and mktempdir docstrings (#38452)

base/file.jl

@@ -638,6 +638,11 @@ tempname()
 Return `(path, io)`, where `path` is the path of a new temporary file in `parent`
 and `io` is an open file object for this path. The `cleanup` option controls whether
 the temporary file is automatically deleted when the process exits.
+
+!!! compat "Julia 1.3"
+    The `cleanup` keyword argument was added in Julia 1.3. Relatedly, starting from 1.3,
+    Julia will remove the temporary paths created by `mktemp` when the Julia process exits,
+    unless `cleanup` is explicitly set to `false`.
 """
 mktemp(parent)
 
@@ -649,6 +654,14 @@ constructed from the given prefix and a random suffix, and return its path.
 Additionally, any trailing `X` characters may be replaced with random characters.
 If `parent` does not exist, throw an error. The `cleanup` option controls whether
 the temporary directory is automatically deleted when the process exits.
+
+!!! compat "Julia 1.2"
+    The `prefix` keyword argument was added in Julia 1.2.
+
+!!! compat "Julia 1.3"
+    The `cleanup` keyword argument was added in Julia 1.3. Relatedly, starting from 1.3,
+    Julia will remove the temporary paths created by `mktempdir` when the Julia process
+    exits, unless `cleanup` is explicitly set to `false`.
 """
 function mktempdir(parent::AbstractString=tempdir();
     prefix::AbstractString=temp_prefix, cleanup::Bool=true)
@@ -705,6 +718,9 @@ end
 
 Apply the function `f` to the result of [`mktempdir(parent; prefix)`](@ref) and remove the
 temporary directory all of its contents upon completion.
+
+!!! compat "Julia 1.2"
+    The `prefix` keyword argument was added in Julia 1.2.
 """
 function mktempdir(fn::Function, parent::AbstractString=tempdir();
     prefix::AbstractString=temp_prefix)