Document how to run examples

[tschundler]

Unlike esp-hal, something like cargo xtask run-example esp-hal-smartled esp32 hello_rgb does not work, and if it did, it isn't documented here.

attempts to cargo run --example hello_rgb --features esp32 were unsuccessful, even adding toolchain.toml to use esp toolchain, and I tried putting these in /cargo/config.toml:

[build]
target = "xtensa-esp32-none-elf"

[target.xtensa-esp32-none-elf]
runner = "espflash flash --monitor"

still no luck. I'm sure it's something simple that I'm missing, but I don't know what.

[akauppi]

I got the example adopted in another repo, but cannot build it here.

$ cargo run --features=esp32c6 --release --example=hello_rgb
[...]
   Compiling rand_core v0.6.4
error[E0583]: file not found for module `arch`
  --> /home/ubuntu/.cargo/registry/src/index.crates.io-6f17d22bba15001f/esp-backtrace-0.14.2/src/lib.rs:46:1
   |
46 | pub mod arch;
   | ^^^^^^^^^^^^^
   |
   = help: to create the module `arch`, create file "/home/ubuntu/.cargo/registry/src/index.crates.io-6f17d22bba15001f/esp-backtrace-0.14.2/src/arch.rs" or "/home/ubuntu/.cargo/registry/src/index.crates.io-6f17d22bba15001f/esp-backtrace-0.14.2/src/arch/mod.rs"
   = note: if there is a `mod arch` elsewhere in the crate already, import it with `use crate::...` instead

   Compiling smart-leds v0.4.0
error[E0425]: cannot find function `backtrace` in module `crate::arch`
  --> /home/ubuntu/.cargo/registry/src/index.crates.io-6f17d22bba15001f/esp-backtrace-0.14.2/src/lib.rs:69:34
   |
69 |     let backtrace = crate::arch::backtrace();
   |                                  ^^^^^^^^^ not found in `crate::arch`

error[E0425]: cannot find value `RA_OFFSET` in module `crate::arch`
  --> /home/ubuntu/.cargo/registry/src/index.crates.io-6f17d22bba15001f/esp-backtrace-0.14.2/src/lib.rs:76:55
   |
76 |         println!("{}0x{:x}", RED, addr - crate::arch::RA_OFFSET);
   |                                                       ^^^^^^^^^ not found in `crate::arch`

Some errors have detailed explanations: E0425, E0583.
For more information about an error, try `rustc --explain E0425`.
error: could not compile `esp-backtrace` (lib) due to 3 previous errors
warning: build failed, waiting for other jobs to finish...

I am not able to understand what's really going on... And the fact that if I depend on esp-hal-smartled and smart-leds from another repository, dependencies are found, makes it a bit more bizarre.

Anyways, can help test.