Fix typo aa -> a in README and doc

Fix typo aa -> a

README.turnserver

@@ -812,7 +812,7 @@ in a batch script). See the file turndb/testsqldbsetup.sql as an example.
 4) The same is true for MySQL database. The same schema file is applicable.
 The same considerations are applicable.
 
-5) The same is true for the Redis database, but the Redis database has aa different schema -
+5) The same is true for the Redis database, but the Redis database has a different schema -
 it can be found (in the form of explanation) in schema.userdb.redis.
 Also, in Redis you can store both "keys" and open passwords (for long term credentials) -
 the "open password" option is less secure but more convenient for low-security environments.

man/man1/turnserver.1

@@ -1114,7 +1114,7 @@ in a batch script). See the file turndb/testsqldbsetup.sql as an example.
 The same is true for MySQL database. The same schema file is applicable.
 The same considerations are applicable.
 .IP 5) 4
-The same is true for the Redis database, but the Redis database has aa different schema \-
+The same is true for the Redis database, but the Redis database has a different schema \-
 it can be found (in the form of explanation) in schema.userdb.redis.
 Also, in Redis you can store both "keys" and open passwords (for long term credentials) \-
 the "open password" option is less secure but more convenient for low\-security environments.