Docs: add notes about dfu-utils

Author: josuah

Docs/learn.md

@@ -239,6 +239,10 @@ An online class was held by tinyVision.ai, and is available freely:
 - [MIT 6.205 Course](https://fpga.mit.edu/6205/F22)
   Requires log-in to access the whole content, but good introductory text.
 
+- [ECE 5760 Course](https://people.ece.cornell.edu/land/courses/ece5760/)
+  A class that widely publishes their teaching material, allowing 3rd-party
+  students to attempt it on their own.
+
 ## Other lists
 
 - [F4PGA Link list](https://github.com/f4pga/ideas/issues/52)

Docs/programming_the_fpga.md

@@ -114,19 +114,17 @@ Several pico-ice-sdk [examples](https://github.com/tinyvision-ai-inc/pico-ice-sd
 On Windows, you can run these examples from the cygwin environment,
 under which you can navigate to the example repositories and try them.
 
-If you used `apio` to install OSS CAD Suite,
-then you can use the APIO install directory as well:
-`export OSS_CAD_SUITE="$HOME/.apio/packages/tools-oss-cad-suite/"`.
 
 
-## F.A.Q.
+You can access the utilities directly from a shell environment after adding the
+`$OSS_CAD_SUITE` to the `$PATH`.
 
-### Q: Why is specifying the OSS_CAD_SUITE directory needed?
+If you used `apio` to install OSS CAD Suite:
 
-APIO installs OSS-CAD-Suite, but it is not possible to directly call the commands from the shell environment
-so it is needed to provide the full path to the binaries to execute them.
-
-With OSS-CAD-Suite, there is a script to source in the current shell environment to avoid this, but if the user forgets, then nothing works.
+```
+export OSS_CAD_SUITE="$HOME/.apio/packages/tools-oss-cad-suite"
+export PATH="$PATH:$OSS_CAD_SUITE/bin"
+```
 
 
 ## Troubleshooting
@@ -159,6 +157,33 @@ This error might occur when a communication error occurs.
 - On Linux operating system, it might need to be allowed with an udev rule,
   or `dfu-util` might need to be run as super user.
 
+To create an udev rule, add a file named `/etc/udev/rules.d/99-pico-ice.rules` with this content:
+
+```
+SUBSYSTEM=="usb", ATTRS{idVendor}=="1209", ATTRS{idProduct}=="b1c0", MODE="0666"
+```
+
+Then reboot or run the following commands:
+
+```
+sudo udevadm control --reload-rules
+sudo udevadm trigger
+```
+
+### dfu-util has multiple devices
+
+For devices with multiple DFU devices connected, the `--device 1209:b1c0` flag is needed:
+
+```
+dfu-util --reset --alt 0 --download rgb_blink.bin --device 1209:b1c0
+```
+
+Alternatively, the `dfu-util --list` result will allow selecting a device per number:
+
+```
+dfu-util --reset --alt 0 --download rgb_blink.bin --devnum 0
+```
+
 ### dfu-util is stuck while uploading before anything could be sent
 
 This could be due that there was no response from the flash chip, and the RP2040 is endlessy waiting the write confirmation.