Update README since status is much more stable

Author: earlephilhower

README.md

@@ -1,13 +1,10 @@
 # arduino-pico
 Raspberry Pi Pico Arduino core, for all RP2040 boards
 
-This is an under-development port of the RP2040 (Raspberry Pi Pico processor) to the Arduino ecosystem.
+This is a port of the RP2040 (Raspberry Pi Pico processor) to the Arduino ecosystem.
 
 It uses a custom toolset with GCC 10.2 and Newlib 4.0.0, not depending on system-installed prerequisites.  https://github.com/earlephilhower/pico-quick-toolchain
 
-The biggest hurdle was getting a working build system outside of the pick-sdk CMake environment.
-Presently, a manually build `pico.a` file is generated using objects compiled by `cmake` in the pico-examples repo, but in the future this will be scripted and automated.
-
 There is automated discovery of boards in bootloader mode, so they show up in the IDE, and the upload command works using the Microsoft UF2 tool (included).
 
 To install:
@@ -31,14 +28,14 @@ The RP2040 PIO state machines (SMs) are used to generate jitter-free:
 Lots of things are working now!
 * digitalWrite/Read (basic sanity tested)
 * shiftIn/Out (tested using Nokia5110 https://github.com/ionpan/Nokia5110)
-* SPI (tested using SdFat 2.0 https://github.com/greiman/SdFat ... note that the Pico voltage regulator can't reliably supply enough power for a SD Card so use external power)
+* SPI (tested using SdFat 2.0 https://github.com/greiman/SdFat ... note that the Pico voltage regulator can't reliably supply enough power for a SD Card so use external power, and adjust the `USE_SIMPLE_LITTLE_ENDIAN` define in `src/sdfat.h` to 0)
 * analogWrite/PWM (tested using Fade.ino)
 * tone/noTone (using IRQ generated waveform)
 * Wire/I2C (tested using DS3231 https://github.com/rodan/ds3231)
 * EEPROM (tested examples)
 * USB Serial(ACM) w/automatic reboot-to-UF2 upload)
 * Hardware UART
-* Servo (basic waveform testing)
+* Servo (basic waveform testing, disables/re-enables without any short pulses)
 
 If you want to contribute or have bugfixes, drop me a note at <[email protected]> or open an issue/PR here.