Fix confusing writing in Your first 3D shader (#4627)

Co-authored-by: Hugo Locurcio <[email protected]>

tutorials/shaders/your_first_shader/your_first_3d_shader.rst

@@ -305,7 +305,7 @@ do that by passing in a second noise texture.
   uniform sampler2D normalmap;
 
 Set this second uniform texture to another NoiseTexture with another
-OpenSimplexNoise. But this time, check off "As Normalmap".
+OpenSimplexNoise. But this time, check **As Normalmap**.
 
 .. image:: img/normal-set.png