docs: document IfLifting as experimental

Author: AayushSabharwal

src/systems/if_lifting.jl

@@ -410,6 +410,11 @@ If lifting converts (nested) if statements into a series of continuous events +
 Lifting proceeds through the following process:
 * rewrite comparisons to be of the form eqn [op] 0; subtract the RHS from the LHS 
 * replace comparisons with generated parameters; for each comparison eqn [op] 0, generate an event (dependent on op) that sets the parameter
+
+!!! warn
+
+    This is an experimental simplification pass. It may have bugs. Please open issues with
+    MWEs for any bugs encountered while using this.
 """
 function IfLifting(sys::System)
     if !is_time_dependent(sys)