Fix typo configuration.rst

docs/configuration.rst

@@ -164,7 +164,7 @@ To have the account created automatically, you just need to define a few environ
 - ``INITIAL_ADMIN_PW``: the admin password.
 - ``INITIAL_ADMIN_MODE``: use one of the options below for configuring how the admin account must be created:
   
-  - ``create``: (default) creates a new admin account and raises an exception when already exists.
+  - ``create``: (default) creates a new admin account and raises an exception when it already exists.
   - ``ifmissing``: creates a new admin account when the admin account does not exist.
   - ``update``: creates a new admin account when it does not exist, or update the password of an existing admin account.