Update extension-manager desciption/icon (#78)

* Update pika-backup.md

* Improve formatting of features list in pika-backup.md

Fixed formatting for the list of features in the documentation.

* Add files via upload

* Enhance extension-manager documentation

Added features section and updated site/source links.

Author: Shikakiben

apps/extension-manager.md

@@ -1,8 +1,26 @@
 # EXTENSION-MANAGER
 
  A native tool for browsing, installing, and managing GNOME Shell Extensions
+ 
+![Screenshot](https://github.com/Shikakiben/extension-manager/blob/master/data/screenshot-installed-light.png#gh-light-mode-only)
 
- SITE/SOURCE: https://github.com/Shikakiben/Extension-Manager-AppImage
+
+## Features
+The tool supports:
+ - Browsing and searching extensions from `extensions.gnome.org`
+ - Installation and Removal
+ - Enabling and Disabling
+ - Updating in-app ([GNOME 43+](https://github.com/mjakeman/extension-manager/wiki/Known-Issue:-Updates))
+ - Screenshots & Images
+ - Ratings & Comments
+ - Translations ([add your language!](#-translations))
+
+If there's something you'd like to see, contributions are welcome!
+
+
+ SITE:https://github.com/mjakeman/extension-manager
+ 
+ SOURCE: https://github.com/Shikakiben/Extension-Manager-AppImage
 
  | [Applications](https://portable-linux-apps.github.io/apps.html) | [Home](https://portable-linux-apps.github.io)
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