tests: variable interpolation comments

To make same as in test_wildcard-host.yml

test/test_custom/test_location-per-vhost.yml

@@ -27,4 +27,4 @@ services:
       - "83"
     environment:
       WEB_PORTS: "83"
-      VIRTUAL_HOST: ~^regex.*\.nginx-proxy\.example$$
+      VIRTUAL_HOST: ~^regex.*\.nginx-proxy\.example$$ # we need to double the `$` because of docker compose variable interpolation

test/test_custom/test_per-vhost.yml

@@ -27,4 +27,4 @@ services:
       - "83"
     environment:
       WEB_PORTS: "83"
-      VIRTUAL_HOST: ~^regex.*\.nginx-proxy\.example$$
+      VIRTUAL_HOST: ~^regex.*\.nginx-proxy\.example$$ # we need to double the `$` because of docker compose variable interpolation

test/test_htpasswd/test_htpasswd-regex-virtual-host.yml

@@ -5,4 +5,4 @@ services:
       - "80"
     environment:
       WEB_PORTS: "80"
-      VIRTUAL_HOST: ~^regex.*\.nginx-proxy\.example$$
+      VIRTUAL_HOST: ~^regex.*\.nginx-proxy\.example$$ # we need to double the `$` because of docker compose variable interpolation