Fix spelling typos

doc/tutorials/gapi/anisotropic_segmentation/porting_anisotropic_segmentation.markdown

@@ -153,7 +153,7 @@ file name before running the application, e.g.:
 
     $ GRAPH_DUMP_PATH=segm.dot ./bin/example_tutorial_porting_anisotropic_image_segmentation_gapi
 
-Now this file can be visalized with a `dot` command like this:
+Now this file can be visualized with a `dot` command like this:
 
     $ dot segm.dot -Tpng -o segm.png
 
@@ -368,7 +368,7 @@ visualization like this:
 
 ![Anisotropic image segmentation graph with OpenCV & Fluid kernels](pics/segm_fluid.gif)
 
-This graph doesn't differ structually from its previous version (in
+This graph doesn't differ structurally from its previous version (in
 terms of operations and data objects), though a changed layout (on the
 left side of the dump) is easily noticeable.
 

doc/tutorials/gapi/face_beautification/face_beautification.markdown

@@ -427,7 +427,7 @@ the ROI, which will lead to accuracy improvement.
 Unfortunately, another problem occurs if we do that:
 if the rectangular ROI is near the border, a describing square will probably go
 out of the frame --- that leads to errors of the landmarks detector.
-To aviod such a mistake, we have to implement an algorithm that, firstly,
+To avoid such a mistake, we have to implement an algorithm that, firstly,
 describes every rectangle by a square, then counts the farthest coordinates
 turned up to be outside of the frame and, finally, pads the source image by
 borders (e.g. single-colored) with the size counted. It will be safe to take

doc/tutorials/gapi/interactive_face_detection/interactive_face_detection.markdown

@@ -145,7 +145,7 @@ description requires three parameters:
    regular "functions" which take and return data. Here network
    `Faces` (a detector) takes a cv::GMat and returns a cv::GMat, while
    network `AgeGender` is known to provide two outputs (age and gender
-   blobs, respecitvely) -- so its has a `std::tuple<>` as a return
+   blobs, respectively) -- so its has a `std::tuple<>` as a return
    type.
 3. A topology name -- can be any non-empty string, G-API is using
    these names to distinguish networks inside. Names should be unique