Fix a typo in 03_ticket_v1/08_stack (#19)

The type argument of `size_of` is `<u8>` instead of `<String>`.

diff --git a/book/src/03_ticket_v1/08_stack.md b/book/src/03_ticket_v1/08_stack.md
index 242d79e..10571ce 100644 (file)
--- a/book/src/03_ticket_v1/08_stack.md
+++ b/book/src/03_ticket_v1/08_stack.md
@@ -45,7 +45,7 @@ using the [`std::mem::size_of`](https://doc.rust-lang.org/std/mem/fn.size_of.htm
 For a `u8`, for example:
 
 ```rust
-// We'll explain this funny-looking syntax (`::<String>`) later on.
+// We'll explain this funny-looking syntax (`::<u8>`) later on.
 // Ignore it for now.
 assert_eq!(std::mem::size_of::<u8>(), 1);
 ```
@@ -59,4 +59,4 @@ assert_eq!(std::mem::size_of::<u8>(), 1);
 [^stack-overflow]: If you have nested function calls, each function pushes its data onto the stack when it's called but
    it doesn't pop it off until the innermost function returns.
    If you have too many nested function calls, you can run out of stack space—the stack is not infinite!
-   That's called a [**stack overflow**](https://en.wikipedia.org/wiki/Stack_overflow).
\ No newline at end of file
+   That's called a [**stack overflow**](https://en.wikipedia.org/wiki/Stack_overflow).