Adds note about correct usage of the dlls section of tgs3.json

.github/CONTRIBUTING.md

@@ -266,6 +266,8 @@ This prevents nesting levels from getting deeper then they need to be.
 
 * Changes to the `/config` tree must be made in a way that allows for updating server deployments while preserving previous behaviour. This is due to the fact that the config tree is to be considered owned by the user and not necessarily updated alongside the remainder of the code. The code to preserve previous behaviour may be removed at some point in the future given the OK by maintainers.
 
+* The dlls section of tgs3.json is not designed for dlls that are purely `call()()`ed since those handles are closed between world reboots. Only put in dlls that may have to exist between world reboots.
+
 #### Enforced not enforced
 The following coding styles are not only not enforced at all, but are generally frowned upon to change for little to no reason: