Improve real-time reference docs. (#4808)

* Improve real-time reference docs.

* Change 'the user' to 'you'.

* Separate listening and fetching.

Author: danasilver

firebase-config/src/main/java/com/google/firebase/remoteconfig/ConfigUpdate.java

@@ -18,10 +18,7 @@
 import com.google.auto.value.AutoValue;
 import java.util.Set;
 
-/**
- * Information about the updated config passed to the {@code onUpdate} callback of {@link
- * ConfigUpdateListener}.
- */
+/** Information about the updated config passed to {@link ConfigUpdateListener#onUpdate}. */
 @AutoValue
 public abstract class ConfigUpdate {
   @NonNull

firebase-config/src/main/java/com/google/firebase/remoteconfig/ConfigUpdateListener.java

@@ -18,21 +18,23 @@
 import javax.annotation.Nonnull;
 
 /**
- * Event listener interface for real-time RC updates. Implement {@code ConfigUpdateListner} to call
- * {@link com.google.firebase.remoteconfig.FirebaseRemoteConfig#addOnConfigUpdateListener}.
+ * Event listener interface for real-time Remote Config updates. Implement {@link
+ * ConfigUpdateListener} to call {@link
+ * com.google.firebase.remoteconfig.FirebaseRemoteConfig#addOnConfigUpdateListener}.
  */
 public interface ConfigUpdateListener {
   /**
-   * Callback for when a new config has been automatically fetched from the backend and has changed
-   * from the activated config.
+   * Callback for when a new config version has been automatically fetched from the backend and has
+   * changed from the activated config.
    *
-   * @param configUpdate A {@link ConfigUpdate} with information about the updated config, including
-   *     the set of updated parameters.
+   * @param configUpdate A {@link ConfigUpdate} with information about the updated config version,
+   *     including the set of updated parameters.
    */
   void onUpdate(@NonNull ConfigUpdate configUpdate);
 
   /**
-   * Callback for when an error occurs while listening or fetching a config update.
+   * Callback for when an error occurs while listening for updates or fetching the latest version of
+   * the config.
    *
    * @param error A {@link FirebaseRemoteConfigException} with information about the error.
    */

firebase-config/src/main/java/com/google/firebase/remoteconfig/FirebaseRemoteConfig.java

@@ -549,21 +549,21 @@ public Task<Void> reset() {
   }
 
   /**
-   * Start listening for real-time config updates from the Remote Config backend and automatically
-   * fetch updates from the RC backend when they are available.
+   * Starts listening for real-time config updates from the Remote Config backend and automatically
+   * fetches updates from the RC backend when they are available.
    *
    * <p>If a connection to the Remote Config backend is not already open, calling this method will
    * open it. Multiple listeners can be added by calling this method again, but subsequent calls
    * re-use the same connection to the backend.
    *
    * <p>Note: Real-time Remote Config requires the Firebase Remote Config Realtime API. See the <a
-   * href="https://firebase.google.com/docs/remote-config/get-started">Remote Config Get Started
-   * </a> guide to enable the API.
+   * href="https://firebase.google.com/docs/remote-config/get-started#add-real-time-listener">Remote
+   * Config Get Started </a> guide to enable the API.
    *
    * @param configUpdateListener A {@link ConfigUpdateListener} that can be used to respond to
    *     config updates when they're fetched.
-   * @return A {@link ConfigUpdateListenerRegistration} that allows the user to remove the added
-   *     {@code configUpdateListener} and close the connection when there are no more listeners.
+   * @return A {@link ConfigUpdateListenerRegistration} that allows you to remove the added {@code
+   *     configUpdateListener} and close the connection when there are no more listeners.
    */
   @NonNull
   public ConfigUpdateListenerRegistration addOnConfigUpdateListener(

firebase-config/src/main/java/com/google/firebase/remoteconfig/FirebaseRemoteConfigClientException.java

@@ -45,7 +45,7 @@ public FirebaseRemoteConfigClientException(@NonNull String detailMessage, @NonNu
 
   /**
    * Creates a Firebase Remote Config client exception with the given message, exception cause, and
-   * FirebaseRemoteConfigException code.
+   * {@code FirebaseRemoteConfigException} code.
    */
   public FirebaseRemoteConfigClientException(
       @NonNull String detailMessage, @Nullable Throwable cause, @NonNull Code code) {

firebase-config/src/main/java/com/google/firebase/remoteconfig/FirebaseRemoteConfigServerException.java

@@ -45,8 +45,8 @@ public FirebaseRemoteConfigServerException(
   }
 
   /**
-   * Creates a Firebase Remote Config server exception with the given message and
-   * FirebaseRemoteConfigException code.
+   * Creates a Firebase Remote Config server exception with the given message and {@code
+   * FirebaseRemoteConfigException} code.
    */
   public FirebaseRemoteConfigServerException(@NonNull String detailMessage, @Nonnull Code code) {
     super(detailMessage, code);
@@ -55,7 +55,7 @@ public FirebaseRemoteConfigServerException(@NonNull String detailMessage, @Nonnu
 
   /**
    * Creates a Firebase Remote Config server exception with the HTTP status code, given message, and
-   * FirebaseRemoteConfigException code.
+   * {@code FirebaseRemoteConfigException} code.
    */
   public FirebaseRemoteConfigServerException(
       int httpStatusCode, @NonNull String detailMessage, @Nonnull Code code) {
@@ -65,7 +65,7 @@ public FirebaseRemoteConfigServerException(
 
   /**
    * Creates a Firebase Remote Config server exception with the given message, exception cause, and
-   * FirebaseRemoteConfigException code.
+   * {@code FirebaseRemoteConfigException} code.
    */
   public FirebaseRemoteConfigServerException(
       @NonNull String detailMessage, @Nullable Throwable cause, @NonNull Code code) {
@@ -75,7 +75,7 @@ public FirebaseRemoteConfigServerException(
 
   /**
    * Creates a Firebase Remote Config server exception with the HTTP status code, given message,
-   * exception cause, and FirebaseRemoteConfigException code.
+   * exception cause, and {@code FirebaseRemoteConfigException} code.
    */
   public FirebaseRemoteConfigServerException(
       int httpStatusCode,