Fix weird indentation in continue_keyword docs

This format was causing every line in the code examples to have a space
at the start.

library/std/src/keyword_docs.rs

@@ -70,7 +70,7 @@ mod as_keyword {}
 /// A break expression is normally associated with the innermost loop enclosing the
 /// `break` but a label can be used to specify which enclosing loop is affected.
 ///
-///```rust
+/// ```rust
 /// 'outer: for i in 1..=5 {
 ///     println!("outer iteration (i): {i}");
 ///
@@ -87,7 +87,7 @@ mod as_keyword {}
 ///     }
 /// }
 /// println!("Bye.");
-///```
+/// ```
 ///
 /// When associated with `loop`, a break expression may be used to return a value from that loop.
 /// This is only valid with `loop` and not with any other type of loop.
@@ -194,20 +194,20 @@ mod const_keyword {}
 /// When `continue` is encountered, the current iteration is terminated, returning control to the
 /// loop head, typically continuing with the next iteration.
 ///
-///```rust
+/// ```rust
 /// // Printing odd numbers by skipping even ones
 /// for number in 1..=10 {
 ///     if number % 2 == 0 {
 ///         continue;
 ///     }
 ///     println!("{number}");
 /// }
-///```
+/// ```
 ///
 /// Like `break`, `continue` is normally associated with the innermost enclosing loop, but labels
 /// may be used to specify the affected loop.
 ///
-///```rust
+/// ```rust
 /// // Print Odd numbers under 30 with unit <= 5
 /// 'tens: for ten in 0..3 {
 ///     '_units: for unit in 0..=9 {
@@ -220,7 +220,7 @@ mod const_keyword {}
 ///         println!("{}", ten * 10 + unit);
 ///     }
 /// }
-///```
+/// ```
 ///
 /// See [continue expressions] from the reference for more details.
 ///