docs: update halmos command in readme (#152)

README.md

@@ -72,7 +72,7 @@ $ forge test
 
 Once it passes, you can also perform **symbolic testing** to verify the same properties for **all possible inputs** (up to a specified limit):
 ```
-$ halmos
+$ halmos --function test
 [FAIL] testTotalPriceBuggy(uint96,uint32) (paths: 6, time: 0.10s, bounds: [])
 Counterexample: [p_price_uint96 = 39614081294025656978550816768, p_quantity_uint32 = 1073741824]
 ```