Add Immich to Multimedia/Photo Galleries category

Multimedia/Photos_Galleries/README.md

@@ -28,6 +28,15 @@
 * Language : PHP
 * Demo : http://www.igalerie.org/demo
 
+### Immich
+* Website : https://immich.app/
+* Dockerfile : Yes
+* Android app : [Yes](https://play.google.com/store/apps/details?id=app.alextran.immich)
+* F-droid app : [Yes](https://f-droid.org/packages/app.alextran.immich)
+* iOS app : [Yes](https://apps.apple.com/us/app/immich/id1613945652)
+* Language : NodeJS
+* Demo : https://demo.immich.app/
+
 ### Koken
 * Website : http://koken.me/
 * Dockerfile : Yes