Fix internal source documentation (#6372)

Author: paulb777

FirebaseAuth/CHANGELOG.md

@@ -1,3 +1,6 @@
+# v6.9.1
+- [fixed] Internal source documentation. (#6371)
+
 # v6.9.0
 - [added] Added support for multi-tenancy (#6142).
 - [added] Added basic watchOS support. (#4621)

FirebaseAuth/Sources/AuthProvider/GameCenter/FIRGameCenterAuthCredential.h

@@ -50,7 +50,7 @@ NS_ASSUME_NONNULL_BEGIN
 @property(nonatomic, readonly) uint64_t timestamp;
 
 /** @property displayName
-    @brief The date and time that the signature was created.
+    @brief The display name of the local Game Center player.
  */
 @property(nonatomic, readonly) NSString *displayName;
 
@@ -60,6 +60,7 @@ NS_ASSUME_NONNULL_BEGIN
     @param signature The verification signature generated.
     @param salt A random string used to compute the hash and keep it randomized.
     @param timestamp The date and time that the signature was created.
+    @param displayName The display name of the Game Center player.
  */
 - (nullable instancetype)initWithPlayerID:(NSString *)playerID
                              publicKeyURL:(NSURL *)publicKeyURL