docs: move add, subtract and hypotenuse to comparison folder

Author: EscapedGibbon

docs/Features/Comparison/Comparison.md

@@ -0,0 +1,12 @@
+Comparison methods are methods that compare other images for feature matching or change detection by subtraction or addition of image values etc.
+The specific reasons for comparing images depend on the application and the desired outcome. In many cases, it is also a valuable tool for identifying changes, isolating objects, enhancing features, and improving image quality for various purposes.
+
+### Methods that can be applied on Images only
+
+- [add](./add.md 'internal link on add')
+
+- [hypotenuse](./hypotenuse.md 'internal link on hypotenuse')
+
+### Methods that can be applied on Images and Masks
+
+- [subtract](./subtract.md 'internal link on subtract')

docs/Features/Comparison/add.md

@@ -0,0 +1,27 @@
+[Check options and parameters of add method](https://image-js.github.io/image-js-typescript/classes/Image.html#add 'github.io link')
+
+:::caution
+This method works only with images.
+:::
+
+Method called `add`, opposed to [`subtract`](./subtract.md 'internal link on subtract'), takes another Image and makes an addition between each respective pixel.
+It works like this:
+
+```ts
+let mask = new Image(3, 3, {
+  data: new Uint8Array([1, 122, 122, 122, 122, 1, 1, 1, 1]),
+});
+let mask2 = new Image(3, 3, {
+  data: new Uint8Array([1, 133, 133, 133, 0, 0, 50, 0, 1]),
+});
+mask = mask.subtract(mask2);
+// expect mask to equal [2,255,255,255,255,122,1,51,2]
+```
+
+:::caution
+Images must have the same size, channel number and bit depth for compatibility reasons.
+:::
+
+### Parameters and default values
+
+- [`otherImage`](https://image-js.github.io/image-js-typescript/classes/Mask.html#subtract 'github.io link')

docs/Features/Filters/hypotenuse.md renamed to docs/Features/Comparison/hypotenuse.md

@@ -8,10 +8,10 @@ let mask = new Mask(3, 3, {
   data: new Uint8Array([1, 1, 1, 1, 1, 1, 1, 1, 1]),
 });
 let mask2 = new Mask(3, 3, {
-  data: new Uint8Array([1, 1, 1, 2, 2, 2, 2, 2, 2]),
+  data: new Uint8Array([1, 1, 1, 0, 0, 0, 0, 0, 1]),
 });
 mask = mask.subtract(mask2);
-// expect mask to equal [0,0,0,1,1,1,1,1,1]
+// expect mask to equal [0,0,0,1,1,1,1,1,0]
 ```
 
 :::caution
@@ -20,7 +20,7 @@ Both masks must have the same size for compatibility reasons. Images must have t
 
 ### Parameters and default values
 
-- [`mask`](https://image-js.github.io/image-js-typescript/classes/Mask.html#subtract 'github.io link')
+- [`other`](https://image-js.github.io/image-js-typescript/classes/Mask.html#subtract 'github.io link')
 
 - [`options`](https://image-js.github.io/image-js-typescript/classes/Mask.html#subtract 'github.io link')
 

docs/Features/Filters/subtract.md renamed to docs/Features/Comparison/subtract.md

@@ -20,8 +20,6 @@ sidebar_position: 0
 
 - [Median](./Median.md 'internal link on median')
 
-- [hypotenuse](./hypotenuse.md 'internal link on hypotenuse')
-
 - [level](./level.md 'internal link on level')
 
 - [pixelate](./Pixelate.md 'internal link on pixelate')
@@ -35,5 +33,3 @@ sidebar_position: 0
 ### Methods that can be applied on Images or Masks
 
 - [invert](./Invert.md 'internal link on invert')
-
-- [subtract](./subtract.md 'internal link on subtract')