feat: Add grind_pattern on Nat.mod_eq_of_lt

Author: pirapira

src/Init/Data/Nat/Div/Basic.lean

@@ -179,6 +179,9 @@ theorem mod_eq_of_lt {a b : Nat} (h : a < b) : a % b = a :=
     if_neg h'
   (mod_eq a b).symm ▸ this
 
+grind_pattern mod_eq_of_lt => a % b where
+  guard (a < b)
+
 @[simp] theorem one_mod_eq_zero_iff {n : Nat} : 1 % n = 0 ↔ n = 1 := by
   match n with
   | 0 => simp