Update Slovenian translation

Co-authored-by: Damjan Gerl <damjan@damjan.net>

locales/sl.json

@@ -516,5 +516,9 @@
     "generic_button_rss": "RSS",
     "playlist_button_add_items": "Dodaj videoposnetke",
     "channel_tab_podcasts_label": "Poddaje",
-    "channel_tab_releases_label": "Izdaje"
+    "channel_tab_releases_label": "Izdaje",
+    "generic_channels_count_0": "{{count}} kanal",
+    "generic_channels_count_1": "{{count}} kanala",
+    "generic_channels_count_2": "{{count}} kanali",
+    "generic_channels_count_3": "{{count}} kanalov"
 }