fix blocked issue (regex room name)

Author: dimaspirit

samples/webrtc/index.html

@@ -45,7 +45,7 @@ <h3 class="join__title">
                         </div>
 
                         <div class="join__row">
-                            <input type="text" class="join__input" name="room" placeholder="Chat room name" required title="Field should contain alphanumeric characters only in a range 3 to 15, without space. The first character must be a letter." pattern="^[a-zA-Z][\w]{2,14}$">
+                            <input type="text" class="join__input" name="room" placeholder="Chat room name" required title="Field should contain alphanumeric characters only in a range 3 to 15, without space. The first character must be a letter." pattern="^[a-zA-Z][a-zA-Z0-9]{2,14}$">
                         </div>
 
                         <div class="join__row">