docs(Dispatchers.common): Improve & fix grammar (Kotlin#3209)

kotlinx-coroutines-core/common/src/Dispatchers.common.kt

@@ -26,9 +26,9 @@ public expect object Dispatchers {
  *
  * Access to this property may throw an [IllegalStateException] if no main dispatchers are present in the classpath.
  *
- * Depending on platform and classpath it can be mapped to different dispatchers:
+ * Depending on platform and classpath, it can be mapped to different dispatchers:
  * - On JS and Native it is equivalent to the [Default] dispatcher.
- * - On JVM it either the Android main thread dispatcher, JavaFx or Swing EDT dispatcher. It is chosen by the
+ * - On JVM it is either the Android main thread dispatcher, JavaFx or Swing EDT dispatcher. It is chosen by the
  * [`ServiceLoader`](https://docs.oracle.com/javase/8/docs/api/java/util/ServiceLoader.html).
  *
  * In order to work with the `Main` dispatcher, the following artifact should be added to the project runtime dependencies:
@@ -48,7 +48,7 @@ public expect object Dispatchers {
  * stack overflows.
  *
  * ### Event loop
- * Event loop semantics is a purely internal concept and have no guarantees on the order of execution
+ * Event loop semantics is a purely internal concept and has no guarantees on the order of execution
  * except that all queued coroutines will be executed on the current thread in the lexical scope of the outermost
  * unconfined coroutine.
  *
@@ -63,11 +63,11 @@ public expect object Dispatchers {
  * }
  * println("Done")
  * ```
- * Can print both "1 2 3" and "1 3 2", this is an implementation detail that can be changed.
- * But it is guaranteed that "Done" will be printed only when both `withContext` calls are completed.
+ * Can print both "1 2 3" and "1 3 2". This is an implementation detail that can be changed.
+ * However, it is guaranteed that "Done" will be printed only when both `withContext` calls are completed.
  *
  * If you need your coroutine to be confined to a particular thread or a thread-pool after resumption,
- * but still want to execute it in the current call-frame until its first suspension, then you can use
+ * but still want to execute it in the current call-frame until its first suspension, you can use
  * an optional [CoroutineStart] parameter in coroutine builders like
  * [launch][CoroutineScope.launch] and [async][CoroutineScope.async] setting it to
  * the value of [CoroutineStart.UNDISPATCHED].