chore(common): move kb images to dedicated folder

Author: marin-bratanov

knowledge-base/grid-three-level-hierarchy.md

@@ -100,5 +100,5 @@ Put nested `<TelerikGrid>` instances in the `DetailTemplate` of their parents. T
 }
 ````
 
-![](three-level-hierarchy-grid.png)
+![](images/three-level-hierarchy-grid.png)
 

knowledge-base/nested-render-fragment-error.png renamed to knowledge-base/images/nested-render-fragment-error.png

@@ -24,7 +24,7 @@ followed by
 
 > `The child content element 'DetailTemplate' of component 'TelerikGrid' uses the same parameter name ('context') as enclosing child content element 'DetailTemplate' of component 'TelerikGrid'. Specify the parameter name like: '<DetailTemplate Context="another_name"> to resolve the ambiguity`
 
-![](nested-render-fragment-error.png)
+![](images/nested-render-fragment-error.png)
 
 ## Solution