docs: Update comments for regional topics (#967)

Update comments to indicate that topics may belong to a region or zone.

Author: tmdiep

google-cloud-pubsublite/src/main/java/com/google/cloud/pubsublite/LocationPath.java

@@ -54,7 +54,7 @@ public abstract static class Builder extends ProjectLocationBuilderHelper<Builde
   /**
    * Parse a location path. Should be structured like:
    *
-   * <p>projects/&lt;project number&gt;/locations/&lt;cloud zone&gt;
+   * <p>projects/&lt;project number&gt;/locations/&lt;cloud region or zone&gt;
    */
   public static LocationPath parse(String path) throws ApiException {
     String[] splits = path.split("/");

google-cloud-pubsublite/src/main/java/com/google/cloud/pubsublite/SubscriptionPath.java

@@ -26,7 +26,8 @@
 /**
  * A string wrapper representing a subscription. Should be structured like:
  *
- * <p>projects/&lt;project number&gt;/locations/&lt;cloud zone&gt;/subscriptions/&lt;id&gt;
+ * <p>projects/&lt;project number&gt;/locations/&lt;cloud region or
+ * zone&gt;/subscriptions/&lt;id&gt;
  */
 @AutoValue
 public abstract class SubscriptionPath implements Serializable {

google-cloud-pubsublite/src/main/java/com/google/cloud/pubsublite/TopicPath.java

@@ -26,7 +26,7 @@
 /**
  * A string wrapper representing a topic. Should be structured like:
  *
- * <p>projects/&lt;project number&gt;/locations/&lt;cloud zone&gt;/topics/&lt;id&gt;
+ * <p>projects/&lt;project number&gt;/locations/&lt;cloud region or zone&gt;/topics/&lt;id&gt;
  */
 @AutoValue
 public abstract class TopicPath implements Serializable {

samples/snippets/src/test/java/pubsublite/QuickStartIT.java

@@ -44,7 +44,7 @@ public class QuickStartIT {
 
   private static final Long projectNumber =
       Long.parseLong(System.getenv("GOOGLE_CLOUD_PROJECT_NUMBER"));
-  private String cloudRegion = "us-west1";
+  private String cloudRegion = "us-central1";
   private final char zoneId = (char) (rand.nextInt(3) + 'a');
   private static final String suffix = UUID.randomUUID().toString();
   private static final String reservationId = "lite-reservation-" + suffix;