Clarify texture coordinates

Author: SaschaWillems

en/06_Texture_mapping/02_Combined_image_sampler.adoc

@@ -112,8 +112,8 @@ The descriptors are now ready to be used by the shaders!
 
 == Texture coordinates
 
-There is one important ingredient for texture mapping that is still missing, and that's the actual coordinates for each vertex.
-The coordinates determine how the image is actually mapped to the geometry.
+There is one important ingredient for texture mapping that is still missing, and that's the actual texture coordinates for each vertex, often called "uv coordinates".
+The texture coordinates determine how the image is actually mapped to the geometry.
 
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