add warning about crossplay + stack limits

system/config.example.json

@@ -673,14 +673,21 @@
   ],
 
   // Item stack limits. Note that changing these does not affect the client's
-  // behavior automatically - this only exists to allow the server to understand
-  // the behavior of clients that are already patched with different stack
-  // limits. If you want to use an unpatched BB client but still have custom
-  // stack limits, you can use the StackLimits runtime patch by editing
+  // behavior automatically - this only exists to allow the server to
+  // understand the behavior of clients that are already patched with different
+  // stack limits.
+  // If you want to use an unpatched BB client but still have custom stack
+  // limits, you can use the StackLimits runtime patch by editing
   // system/client-functions/BlueBurstExclusive/StackLimits.59NL.patch.s to
-  // match the BB stack limits and adding "StackLimits" to the BBRequiredPatches
-  // list. The ToolLimits list is indexed by data1[1] (that is, the second byte
-  // of the item data); for items beyond the end of the list, the last entry's
+  // match the BB stack limits and adding "StackLimits" to the
+  // BBRequiredPatches list.
+  // It's important that all players in the same game have the same stack
+  // limits, both on the client and server! So, if you change the BB stack
+  // limits, you must either prevent BB from playing with other versions (see
+  // CompatibilityGroups) or write an analogous patch for all other versions
+  // and add it to AutoPatches.
+  // The ToolLimits list is indexed by data1[1] (that is, the second byte of
+  // the item data); for items beyond the end of the list, the last entry's
   // value is used.
   "ItemStackLimits": [
     {"MesetaLimit": 999999, "ToolLimits": [10]}, // DC NTE