Add docstring

Author: Serock3

talpid-wireguard/src/lib.rs

@@ -1003,6 +1003,11 @@ mod mtu_detection {
 
     use super::Error;
 
+    /// Verify that the current MTU doesn't cause dropped packets, otherwise lower it to the
+    /// largest value which doesn't.
+    ///
+    /// Note: This does not take fragmentation into account, so it should only be used as an extra
+    /// safety measure after the normal MTU calculation using header sizes and safety margins.
     pub async fn automatic_mtu_correction(
         gateway: std::net::Ipv4Addr,
         iface_name_clone: String,