[Verif] Fix markdown header level; NFC

Author: fabianschuiki

include/circt/Dialect/Verif/VerifOps.td

@@ -297,7 +297,7 @@ def FormalOp : VerifOp<"formal", [
     into the hardware to be tested. Testing tools will then try to find concrete
     values for them that violate any asserts or make any covers true.
 
-    ### Example
+    #### Example
     ```
     verif.formal @AdderTest {myParam = 42, myTag = "hello"} {
       %0 = verif.symbolic_value : i42
@@ -309,7 +309,7 @@ def FormalOp : VerifOp<"formal", [
     }
     ```
 
-    ### Parameters
+    #### Parameters
     The following parameters have a predefined meaning and are interpreted by
     tools such as `circt-test` to guide execution of tests:
 
@@ -362,15 +362,15 @@ def SimulationOp : VerifOp<"simulation", [
     by various tools. To describe a test, the body of this op should contain the
     hardware to be tested, alongside any necessary forms of stimulus generation.
 
-    ### Inputs
+    #### Inputs
 
     The body has two block arguments as input values: a "clock" signal of type
     `!seq.clock` and an "init" signal of type `i1`. The clock signal starts at 0
     and continuously toggles between 0 and 1 throughout the simulation. The init
     signal starts at 1, remains 1 during a single 0-to-1 transition of the
     clock, and then drops to 0 for the remainder of the simulation.
 
-    ### Outputs
+    #### Outputs
 
     The body must have a `verif.yield` terminator op with exactly two operands:
 
@@ -384,7 +384,7 @@ def SimulationOp : VerifOp<"simulation", [
     time as the done signal. Simulators must signal failure to the operating
     system through a non-zero exit code.
 
-    ### Schedule
+    #### Schedule
 
     The clock and init values adhere to the following schedule during
     simulation:
@@ -402,7 +402,7 @@ def SimulationOp : VerifOp<"simulation", [
     Simulation termination occurs when the done signal is 1 during a 0-to-1
     transition of the clock.
 
-    ### Example
+    #### Example
     ```
     verif.simulation @AdderTest {myParam = 42, myTag = "hello"} {
     ^bb0(%clock: !seq.clock, %init: i1):