Clarify that scripting engines are allowed

mods/guidelines.md

@@ -26,7 +26,7 @@ A mod found breaking any of these rules will be **rejected unconditionally** fro
  * The mod features **explicit content and/or profanity**. Note that the source code having comments, variable names, etc. containing profanity is fine, as long as they aren't visible to the end user
  * The mod **does not have appropriate metadata**. All mods on the Index must have a proper name, description, icon, and tags, [including jokes](#joke-mods)
  * The mod **removes Vanilla features** for no good reason
- * The mod **installs other mods from outside the Geode index**. You are not allowed to unsafely run any arbitary code downloaded off the internet. An exception is installing additional paid features as a runtime library; do note that for the purposes of verification, the code for all of those paid features must be included, including the code used to load them.
+ * The mod **installs other mods from outside the Geode index**. You are not allowed to run any arbitary code downloaded off the internet. There are two exceptions to this rule: mods that introduce some sort of scripting system that runs *sandboxed* arbitary code, and mods installing additional paid features as a runtime library. Do note that for the purposes of verification, the code for all of those paid features must be included, including the code used to load them.
 
 A mod found breaking any of these rules will likely be rejected, although depending on the situation, they could also still be approved.