Update docs.

Author: flaviojs

docs.md

@@ -299,24 +299,9 @@ fn bar() -> Foo { .. } // Will be emitted as `struct foo bar();`
 
 ### Volatile annotation
 
-cbindgen will emit the C volatile type qualifier for types and variables that have the `volatile=true` annotation.
+cbindgen will emit the C volatile type qualifier for transparent 1-field structs that have the `volatile` annotation.
 
-There is no equivalent in rust. You should use `read_volatile` and `write_volatile` to get C-like behavior.
-
-```rust
-/// cbindgen:volatile=true
-type volatile_type_t = u32;
-
-#[repr(C)]
-struct S {
-    /// cbindgen:volatile=true
-    volatile_variable: u32,
-}
-
-/// cbindgen:volatile=true
-#[no_mangle]
-static mut volatile_global_variable: u32 = 0;
-```
+Example usage can be found in `tests/rust/volatile.rs`.
 
 ### Struct Annotations
 

tests/rust/volatile.rs

@@ -1,4 +1,4 @@
-//! This test uses the `cbindgen:volatile=true` annotation to generate volatile types and variables.
+//! This test uses the `volatile` annotation on a wrapper to generate volatile types.
 
 use std::ffi::c_int;
 use std::mem::ManuallyDrop;
@@ -8,7 +8,7 @@ use std::ptr::null_mut;
 use std::ptr::NonNull;
 use std::cell::Cell;
 
-/// cbindgen:volatile=true
+/// cbindgen:volatile
 #[repr(transparent)]
 pub struct V<T>(T);
 impl<T> V<T> {
@@ -45,8 +45,8 @@ pub type c_vci = V<Cell<c_int>>;
 
 pub type c_vfn = V<Option<extern "C" fn()>>;
 
-// TODO not FFI-safe
-//pub type c_va2 = [V<c_int>; 2];
+// TODO cannot mangle array
+//pub type c_va2 = V<[c_int; 2]>;
 
 #[repr(C)]
 pub struct S {