Add links to pico-littlefs-usb (FAT12 emulation) and mklittlefs

[geky]

• pico-littlefs-usb

  Implemented by @oyama, pico-littlefs-usb provides an easy interface to littlefs by emulating a FAT12 filesystem over USB.

  There are some tradeoffs to this, but being able to mount a littlefs device without installing additional drivers is very nice. Maybe in the future devices could provide both a FAT and raw endpoint for easy/advanced filesystem access.

• mklittlefs

  Implemented by @earlephilhower, mklittlefs is a command line interface that seems to be used by the ESP8266 and RP2040 ecosystems. It deserves a mention.

Eventually, these (and most links in the README.md) will move to an external wiki. Eventually...

[geky-bot]

Tests passed ✓, Code: 17032 B (+0.0%), Stack: 1432 B (+0.0%), Structs: 812 B (+0.0%)

| | Code | Stack | Structs | | Coverage | |:--|-----:|------:|--------:|:--|---------:| | Default | 17032 B (+0.0%) | 1432 B (+0.0%) | 812 B (+0.0%) | Lines | 2391/2571 lines (+0.0%) | | Readonly | 6190 B (+0.0%) | 448 B (+0.0%) | 812 B (+0.0%) | Branches | 1243/1582 branches (+0.0%) | | Threadsafe | 17896 B (+0.0%) | 1432 B (+0.0%) | 820 B (+0.0%) | | **Benchmarks** | | Multiversion | 17096 B (+0.0%) | 1432 B (+0.0%) | 816 B (+0.0%) | Readed | 29369693876 B (+0.0%) | | Migrate | 18728 B (+0.0%) | 1736 B (+0.0%) | 816 B (+0.0%) | Proged | 1482874766 B (+0.0%) | | Error-asserts | 17712 B (+0.0%) | 1424 B (+0.0%) | 812 B (+0.0%) | Erased | 1568888832 B (+0.0%) |