Remove TBD for device support, link to issue in TODO

Author: rgommers

spec/design_topics/device_support.md

@@ -0,0 +1,6 @@
+.. _device-support:
+
+# Device support
+
+TODO. See https://github.com/data-apis/array-api/issues/39
+

spec/design_topics/index.rst

@@ -11,6 +11,7 @@ Design topics & constraints
    static_typing
    array_ducktyping
    data_interchange
+   device support
    missing_data
    portability
    C_API

spec/purpose_and_scope.md

@@ -29,6 +29,7 @@ The scope of the array API standard includes:
 - Casting rules, broadcasting, indexing
 - Data interchange. I.e. protocols to convert one type of array into another
   type, potentially sharing memory.
+- Device support.
 
 Furthermore, meta-topics included in this standard include:
 
@@ -128,12 +129,6 @@ extensions are dealt with_):
 
 ### TBD whether or not in scope, or for a later version
 
-- Device support (related to array creation on a specific device).
-
-  _This can be important, however there's no uniform syntax for it currently
-  and it may not make sense to add such syntax to libraries that only support a
-  single device type._
-
 - Random number generation, Fourier transforms, and miscellaneous functionality
   like a padding function.