Fix newlines and whitespace in comment

Author: carols10cents

datafusion/physical-plan/src/execution_plan.rs

@@ -267,9 +267,10 @@ pub trait ExecutionPlan: Debug + DisplayAs + Send + Sync {
     /// batch is superlinear. See this [general guideline][async-guideline] for more context
     /// on this point, which explains why one should avoid spending a long time without
     /// reaching an `await`/yield point in asynchronous runtimes.
-    /// This can be achieved by manually returning [`Poll::Pending`] and setting up wakers appropriately, or the use of [`tokio::task::yield_now()`] when appropriate.
+    /// This can be achieved by manually returning [`Poll::Pending`] and setting up wakers
+    /// appropriately, or the use of [`tokio::task::yield_now()`] when appropriate.
     /// In special cases that warrant manual yielding, determination for "regularly" may be
-    /// made using a timer (being careful with the  overhead-heavy system call needed to
+    /// made using a timer (being careful with the overhead-heavy system call needed to
     /// take the time), or by counting rows or batches.
     ///
     /// The cancellation benchmark tracks some cases of how quickly queries can