doc: added small bit of dsocumentaiton

src/methods/change_details.rs

@@ -12,6 +12,8 @@ pub struct LdapUpdate {
     field: String,
     value: String,
 }
+
+/// Handles updating a single field with the users own password
 pub async fn post_update_ldap(mut req: Request<State>) -> tide::Result {
     let LdapUpdate {
         user,