vhost: Support regex matching paths

roles/vhost/meta/argument_specs.yaml

@@ -378,7 +378,9 @@ argument_specs:
         elements: dict
         options:
           path:
-            description: Path to match. Only supports full paths for now.
+            description: >-
+              Path to match.
+              If the value begins with ^ and end with $, the value is matched as regex.
             type: str
             required: true
           type:
@@ -565,8 +567,7 @@ argument_specs:
               match_headers:
                 description: >-
                   Headers to match against.
-                  The value is matched as regex.
-                  ^ and $ are implied, so don't add them yourself.
+                  If the value begins with ^ and end with $, the value is matched as regex.
                 type: dict
                 required: false
                 default: {}