Update flow.md (#2196)

Author: MasoodFallahpoor

docs/flow.md

@@ -50,7 +50,7 @@
 
 ## Asynchronous Flow
 
-Suspending functions asynchronously returns a single value, but how can we return
+A suspending function asynchronously returns a single value, but how can we return
 multiple asynchronously computed values? This is where Kotlin Flows come in.
 
 ### Representing multiple values