Update docs/src/catalyst_applications/simulation_structure_interfacing.md

Co-authored-by: Sam Isaacson <[email protected]>

Author: TorkelE

docs/src/catalyst_applications/simulation_structure_interfacing.md

@@ -27,7 +27,7 @@ with the notation being identical for parameters:
 oprob[:k1]
 ```
 
-If we want to change a unknown's initial condition value, we use the following notation
+If we want to change an unknown's initial condition value, we use the following notation
 ```@example ex1
 oprob[:X1] = 10.0
 ```