carts: Merge DS and DSi cartridges sections

Author: AntonioND

content/SUMMARY.md

@@ -10,7 +10,6 @@
         * [3D Display Control](3d_disp_cnt.md)
     * [DS Sound](ds_sound.md)
     * [DS Peripherals](ds_peripherals.md)
-    * [DS Cartridges](ds_cartridges.md)
     * [DS WiFi (Mitsumi)](ds_wifi.md)
 * [DSi Introduction](dsi_introduction.md)
     * [DSi I/O Map](dsi_io_map.md)
@@ -24,10 +23,10 @@
     * [DSi SD/MMC](dsi_sd_mmc.md)
     * [DSi GPIO](dsi_gpio.md)
     * [DSi AES Engine](dsi_aes.md)
-    * [DSi Cartridges](dsi_cartridges.md)
     * [DSi WiFi (Atheros)](dsi_wifi.md)
     * [DSi DSP (XpertTeak)](dsi_dsp_xpertteak.md)
 * [Other](other.md)
+    * [DS Cartridges](ds_cartridges.md)
     * [ROM Header](rom_header.md)
     * [CPU Reference](cpu_reference.md)
     * [BIOS Functions](bios.md)