Mention duplicate tasks in execute_async()

src/context.rs

@@ -53,6 +53,12 @@ pub trait InitContext<P: Plugin> {
 pub trait ProcessContext<P: Plugin> {
     /// Run a task on a background thread. This allows defering expensive background tasks for
     /// alter. As long as creating the `task` is realtime-safe, this operation is too.
+    ///
+    /// # Note
+    ///
+    /// Scheduling the same task multiple times will cause those duplicate tasks to pile up. Try to
+    /// either prevnt this from happening, or check whether the task still needs to be completed in
+    /// your task executor.
     fn execute_async(&self, task: P::BackgroundTask);
 
     /// Get the current plugin API.