added doc metadata, use RTT panic target

- Use RTT panic target in blinky button example

Cargo.toml

@@ -10,8 +10,10 @@ license = "MIT OR Apache-2.0"
 keywords = ["no-std", "reb1", "cortex-m", "vorago", "va108xx"]
 categories = ["embedded", "no-std", "hardware-support"]
 
-[dependencies]
+[package.metadata.docs.rs]
+features = ["rt"]
 
+[dependencies]
 cortex-m = "0.7.3"
 cortex-m-rt = "0.7.0"
 embedded-hal = "0.2.6"

examples/blinky-button-irq.rs

@@ -6,7 +6,7 @@ use core::cell::{Cell, RefCell};
 
 use cortex_m::interrupt::Mutex;
 use cortex_m_rt::entry;
-use panic_halt as _;
+use panic_rtt_target as _;
 use rtt_target::{rprintln, rtt_init_print};
 use va108xx_hal::{
     clock::{set_clk_div_register, FilterClkSel},