Fix variable name typo

roles/custom/matrix-synapse/defaults/main.yml

@@ -297,7 +297,7 @@ matrix_synapse_container_extra_arguments_auto: []
 matrix_synapse_container_arguments: "{{ matrix_synapse_container_extra_arguments + matrix_synapse_container_extra_arguments_auto }}"
 
 # matrix_synapse_container_master_extra_arguments contains arguments specific to the master process whereas
-# matrix_synapse_container_extra_arguments contains arguments the apply to all synapse worker processes.
+# matrix_synapse_container_arguments contains arguments the apply to all Synapse containers (master and worker).
 matrix_synapse_container_master_extra_arguments: []
 
 # List of systemd services that matrix-synapse.service depends on