more docs, sort examples

examples/0-agnostic.rs

@@ -0,0 +1,15 @@
+//! Device agnostic "Hello, world!"
+//!
+//! Prints "Hello, world!" on the OpenOCD console using semihosting
+
+#![feature(used)]
+#![no_std]
+
+extern crate cortex_m_rt;
+
+fn main() {}
+
+#[allow(dead_code)]
+#[used]
+#[link_section = ".rodata.interrupts"]
+static INTERRUPTS: [u32; 240] = [0; 240];