Add debugger tip to section "Trace a Tree Creation Site" of the contributing guide

[Cherry-picked efa9203]

Author: Sporarum

docs/_docs/contributing/issues/cause.md

@@ -38,6 +38,9 @@ the tree was generated by looking for its unique ID, and then generating a stack
 3. Run the compiler with `-Ydebug-tree-with-id <tree-id>` flag. The compiler will print a stack trace
    pointing to the creation site of the tree with the provided ID.
 
+If you are using a debugger, you can add a breakpoint in the `ownId == debugId` section of method `allocateId` of `Positioned.scala` (you will still need the flag), this will allow you to navigate the stack with more ease.
+Do not use a conditional breakpoint, the time overhead is very significant for a method called as often as this one.
+
 ### Enhanced Tree Printing
 
 As seen above `-Xprint:<phase>` can be enhanced with further configuration flags, found in