make mdbook test pass by not opening local files or running shell scr…

…ipts on Windows

training-slides/src/io.md

@@ -90,7 +90,7 @@ See the [std::io::File docs](https://doc.rust-lang.org/std/fs/struct.File.html#i
   * Owns a `R: Read`, and `impl BufRead`
   * Has a buffer in RAM and reads in large-ish chunks
 
-```rust []
+```rust ignore []
 use std::io::BufRead;
 
 fn main() -> std::io::Result<()> {

training-slides/src/std-lib-tour.md

@@ -33,7 +33,7 @@ A process builder, providing fine-grained control over how a new process should
 
 Used for interacting with other executables.
 
-```rust []
+```rust ignore []
 use std::process::Command;
 
 fn main() {