Update Chapter 3 - Akaze feature extraction with correct expected image

[whhuang]

Chapter 3 of the tutorial has the incorrect expected image. The tutorial shows an image with feature matching:

but the code that is being run in Chapter 3 of the tutorial only extracts AKAZE feature and draws them on a single image with crosses, which is consistent with the rest of the chapter:

The image in the tutorial is located at https://rust-cv.github.io/res/tutorial-images/akaze-result.png, so instead of updating the source, the image at that URL can just be updated to the correct one instead.

[vadixidav]

Thank you. I will look later at what I need to update before I merge this.

[whhuang]

@vadixidav thanks for taking a look! Also, the image I got from running the Chapter 4 example is actually the one in Chapter 3 (this one), so the image in https://rust-cv.github.io/res/tutorial-images/matches.png needs to be replaced with the image in https://rust-cv.github.io/res/tutorial-images/akaze-result.png.

[vadixidav]

I went ahead and fixed the issue on the rust-cv.github.io side, but I want to make sure you get credit as a contributor, so I am going to add a revert to your branch and then merge it. I know, it's a bit silly, but I think it is important. Thank you!