fix typo

Author: mtrezza

src/Options/Definitions.js

@@ -1120,7 +1120,7 @@ module.exports.LogLevels = {
   usernameAlreadyExists: {
     env: 'PARSE_SERVER_LOG_LEVELS_USERNAME_ALREADY_EXISTS',
     help:
-      'Log level for the username already exists error when trying to sign up.Default is `error`.',
+      'Log level for the username already exists error when trying to sign up. Default is `error`.',
     default: 'error',
   },
 };

src/Options/docs.js

@@ -635,7 +635,7 @@ export interface LogLevels {
   :DEFAULT: error
   */
   cloudFunctionError: ?string;
-  /* Log level for the username already exists error when trying to sign up.Default is `error`.
+  /* Log level for the username already exists error when trying to sign up. Default is `error`.
   :DEFAULT: error
   */
   usernameAlreadyExists: ?string;