fix broken link to API (#2108)

Signed-off-by: Mabel Zhang <[email protected]>

tutorials/terminology.md

@@ -10,14 +10,14 @@ to developers touching the source code.
 
 * **Entity**: Every "object" in the world, such as models, links,
  collisions, visuals, lights, joints, etc.
- An entity [is just a numeric ID](namespace gz_1_1gazebo.html#ad83694d867b0e3a9446b535b5dfd208d),
+ An entity [is just a numeric ID](namespacegz_1_1sim.html#ad83694d867b0e3a9446b535b5dfd208d),
  and may have several components attached to it. Entity IDs are assigned
  at runtime.
 
 * **Component**: Adds a certain functionality or characteristic (e.g., pose,
  name, material, etc.) to an entity.
  Gazebo comes with various
- [components](namespace gz_1_1gazebo_1_1components.html)
+ [components](namespacegz_1_1sim_1_1components.html)
  ready to be used, such as `Pose` and `Inertial`, and downstream developers
  can also create their own by inheriting from the
  [BaseComponent](classignition_1_1gazebo_1_1components_1_1BaseComponent.html)