fix wrong word used (static vs const)

Author: letmaik

src/doc/book/src/const-and-static.md

@@ -32,7 +32,7 @@ static N: i32 = 5;
 Unlike [`let`][let] bindings, you must annotate the type of a `static`.
 
 Statics live for the entire lifetime of a program, and therefore any
-reference stored in a constant has a [`'static` lifetime][lifetimes]:
+reference stored in a static has a [`'static` lifetime][lifetimes]:
 
 ```rust
 static NAME: &'static str = "Steve";