Added photo and videos galleries description

README.md

@@ -1572,6 +1572,8 @@ _Related: [Monitoring](#monitoring), [Bookmarking and Link Sharing](#bookmarks-a
 
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+A [gallery](https://en.wikipedia.org/wiki/Gallery_Software) is software that helps the user publish or share photos, pictures, videos or other digital media.
+
 - [Chevereto Free](https://chevereto.com/free) - Powerful and fast image hosting script that allows you to create your very own full featured image hosting website in just minutes. ([Source Code](https://github.com/Chevereto/Chevereto-Free)) `AGPL-3.0` `PHP`
 - [Coppermine](https://coppermine-gallery.net/) - Multilingual photo gallery that integrates with various bulletin boards. Includes upload approval and password protected albums. ([Demo](https://coppermine-gallery.net/demo/cpg15x/), [Source Code](https://github.com/coppermine-gallery/cpg1.6.x)) `GPL-3.0` `PHP`
 - [Damselfly](https://damselfly.info) - Fast server-based photo management system for large collections of images. Includes face detection, face & object recognition, powerful search, and EXIF Keyword tagging. Runs on Linux, MacOS and Windows. `GPL-3.0` `C#/.NET`