added instructions for proper partition type to sdcard setup

[f1reflyyyylmao]

I tried creating an sd card for my dsi yesterday and couldn't figure out what was going wrong until I looked inside the sdcard_prep.sh and realized the card needs to both have an mbr and the created patrition needs to be marked with a specific type. I think it would be good to include this in the instructions.

[Deletecat]

I don't think rewriting the partition table with fdisk will be necessary here given that this already occurs in Section 1. Instead, I think Section 1 could be tweaked to account for this issue, simply by adding the -f flag to the sdFormatLinux command like so:

- 1. Run `sudo ./sdFormatLinux -e trim /dev/(device name from above)` to format your SD card
+ 1. Run `sudo ./sdFormatLinux -e trim /dev/(device name from above) -f` to format your SD card

After doing some testing, this was enough to fix the partition type issue mentioned -- SD cards are no longer marked as unusable by the DSi software. The mkdosfs command line will still be required in Section 2 for Unlaunch compatibility with SDXC cards (although it could maybe be merged with section 1?). But with that small change in Section 1, I believe that's all that is needed to get SD cards working on the DSi from Linux systems.

[m4gnify]

A bit related I think. The listed instructions for Linux SD card setup didn't work for me. My card got "The device inserted in the SD Card Slot can't be used" even after several tries.

I had a lot of trouble finding a fix, but what ended up fixing it was I ended up using GParted to change the partition to "Cylinder" instead of MiB.

64GB Samsung card

[f1reflyyyylmao]

I think it would still be good to mention that the partition type and table must be set to the specific types. I didn't want to download a random program from the internet when the partition and filesystem operations are all very much doable with the tools I usually use, but the incomplete documentation made this a task of three hours, two of which were spent separating the lower part of the case and cleaning the socket with alcohol and canned air again and again.

[f1reflyyyylmao]

#159 also mentions this issue.

[Epicpkmn11]

imo a tabbed approach like Sanrax's flashcard guide would probably make the most sense for Linux. sdFormatLinux is the ideal tool to use, but then we could still cover other tools

https://sanrax.github.io/flashcart-guides/tutorials/formatting/#__tabbed_1_2