docs: remove colon from time header

notriddle · notriddle · commit 3f5fe0f1174c · 2023-01-28T16:07:34.000-07:00
It's not used anywhere else; the inconsistency is weird.
diff --git a/std/src/time.rs b/std/src/time.rs
@@ -1,6 +1,6 @@
 //! Temporal quantification.
 //!
-//! # Examples:
+//! # Examples
 //!
 //! There are multiple ways to create a new [`Duration`]:
 //!
