Merge pull request #1296 from mbrobbel/patch-1

Re-apply fix for #199 in ch15-05

Author: carols10cents

second-edition/src/ch15-05-interior-mutability.md

@@ -6,11 +6,11 @@
 data even when there are immutable references to that data; normally, this
 action is disallowed by the borrowing rules. To mutate data, the pattern uses
 `unsafe` code inside a data structure to bend Rust’s usual rules that govern
-mutation and borrowing. We haven’t yet covered unsafe code; we will in Chapter
-19. We can use types that use the interior mutability pattern when we can
-ensure that the borrowing rules will be followed at runtime, even though the
-compiler can’t guarantee that. The `unsafe` code involved is then wrapped in a
-safe API, and the outer type is still immutable.
+mutation and borrowing. We haven’t yet covered unsafe code; we will in
+Chapter 19. We can use types that use the interior mutability pattern when we
+can ensure that the borrowing rules will be followed at runtime, even though
+the compiler can’t guarantee that. The `unsafe` code involved is then wrapped
+in a safe API, and the outer type is still immutable.
 
 Let’s explore this concept by looking at the `RefCell<T>` type that follows the
 interior mutability pattern.