Fix header levels.

ielis · ielis · commit 520099af7ee7 · 2025-04-16T17:01:38.000+02:00
diff --git a/src/lib.rs b/src/lib.rs
@@ -87,7 +87,7 @@
 //!
 //! No features are turned on by default.
 //!
-//! ### Optional feature flags
+//! ## Optional feature flags
 //!
 //! The following features customize Phenopackets' behavior:
 //!
