Corrected some typos

phases/constprop.mli

@@ -11,12 +11,12 @@
     the generated code. Note that this can only be applied when the assigned
     expression is a constant or an SSA variable, since these have no side
     effects and will not change in between the assignment and their uses. For
-    optimisation regular of variables, some form of liveness analysis would be
+    optimisation of regular variables, some form of liveness analysis would be
     required.
 
     Constant propagation is supplemented with constand folding and some
     arithmetic simplification, the latter specifically targeting optimisation
-    oppertunities created by earlier constant propagation. For example, in and
+    oppertunities created by earlier constant propagation. For example, in an
     array index calculation when constant array dimensions are propagated, the
     index calculation can often be simplified.