Added note to instructions

Gives some info about debugging.

Exercise3.md

@@ -169,6 +169,10 @@ addition, you may find the following files worth investigating:
 - [The IR AST Definition](ir/teal0/ast/ir.ast)
 - [The IR Improvements for Teal-2](ir/teal2/ast/object.ast) contains so more AST nodes for the Teal-2 IR.
 
+### Debugging
+
+You can print TEAL IR with the line numbers using the flags `-g` and `-s`.
+
 
 ### Arrays in TEAL
 Keep in mind that in TEAL, arrays and indexes are automatically `nonnull`.