Move ImageFiltering.jl examples to JuliaImages demo section

[ashwani-rathee]

ImageFiltering.jl website has three demos

• Custom median filters
• Median/Mean filters
• Template Matching

could be moved to main websites demo section

[johnnychen94]

I like the idea of getting all demos in one place. But it turns out to be a maintenance burden when source codes are in one repo and the documentation(including demos) in the other.

It would be appreciated if there's a syncing tool to get the documentation from, e.g. automatically, ImageFiltering, ImageMorphology, and then build the centralized version here. We can introduce some rules on how files should be organized to make the tool easier to implement.

[ashwani-rathee]

Intending to use MultiDocumenter for this, soon!