Remove duplicate "Project source code URL" from `roles/custom/matrix-synapse/defaults/main.yml`

This was causing issues when it's parsed out by certain tools.

Regression since 28afbde971

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

@@ -1725,8 +1725,6 @@ matrix_synapse_register_user_script_matrix_authentication_service_path: ""
 #
 # When Synapse workers are enabled, however, the reverse-proxying configuration is much more complicated - certain requests need to go to certain workers, etc.
 # matrix-synapse-reverse-proxy-companion is the central place services that need to reach Synapse could be pointed to.
-#
-# Project source code URL: https://github.com/nginx/nginx
 
 matrix_synapse_reverse_proxy_companion_enabled: "{{ matrix_synapse_enabled and matrix_synapse_workers_enabled }}"