Move other uses of 'x' to '×' too for consistency

Identified via:
$ git grep -P '\bx\s*\d+' -- :^images :^package-lock.json :^resources

Author: PeterJCLaw

kit/index.md

@@ -28,7 +28,7 @@ As well as the boards the kit also contains the following items.
 
 | Part                   | Qty | Specification                                      | Notes
 |------------------------|-----|----------------------------------------------------|-------
-| Battery Charger Supply | 1   | 12V 5A, 5.5mmx2.5mm barrel                         | For use with the battery charger
+| Battery Charger Supply | 1   | 12V 5A, 5.5mm × 2.5mm barrel                       | For use with the battery charger
 | Battery Charger        | 1   | iMAX B6 or HobbyKing E4                            | Documentation is available on [charging the batteries](/docs/kit/batteries) using this
 | USB Hub                | 3   | 7-Port                                             | The hub does *not* require a power cable
 | USB Memory Stick       | 1   |                                                    |

kit/return.md

@@ -30,7 +30,7 @@ If you are not returning a complete kit, similar precautions should be used to e
 When shipping the kit with your courier of choice, they may require specific details about the kit:
 
 - Description: Robotics kit
-- Dimensions: 48cm x 39cm x 20cm
+- Dimensions: 48cm × 39cm × 20cm
 - Weight: 6kg (A kit weighs approx. 4.95kg; 6kg gives some headroom)
 - Value (for insurance): £500
 - Batteries: Lithium Ion. Packed with equipment. Batteries less than 100Wh.