Add a capabilities example to the README.md file.

README.md

@@ -27,6 +27,33 @@ and this to your source code:
 use bitflags::bitflags;
 ```
 
+## Example
+
+Generate a flags structure:
+
+```rust
+use bitflags::bitflags;
+
+// The `bitflags!` macro generates `struct`s that manage a set of flags.
+bitflags! {
+    struct Flags: u32 {
+        const A = 0b00000001;
+        const B = 0b00000010;
+        const C = 0b00000100;
+        const ABC = Self::A.bits | Self::B.bits | Self::C.bits;
+    }
+}
+
+fn main() {
+    let e1 = Flags::A | Flags::C;
+    let e2 = Flags::B | Flags::C;
+    assert_eq!((e1 | e2), Flags::ABC);   // union
+    assert_eq!((e1 & e2), Flags::C);     // intersection
+    assert_eq!((e1 - e2), Flags::A);     // set difference
+    assert_eq!(!e2, Flags::A);           // set complement
+}
+```
+
 ## Rust Version Support
 
 The minimum supported Rust version is 1.46 due to use of associated constants and const functions.