[mod] categories: move app search engines to it category instead of files

searx/engines/apkmirror.py

@@ -21,7 +21,7 @@ about = {
 }
 
 # engine dependent config
-categories = ['files', 'apps']
+categories = ['it', 'apps']
 paging = True
 time_range_support = False
 

searx/engines/apple_app_store.py

@@ -17,7 +17,7 @@ about = {
     "results": 'JSON',
 }
 
-categories = ['files', 'apps']
+categories = ['it', 'apps']
 safesearch = True
 
 search_url = 'https://itunes.apple.com/search?{query}'

searx/engines/fdroid.py

@@ -17,7 +17,7 @@ about = {
 }
 
 # engine dependent config
-categories = ['files', 'apps']
+categories = ['it', 'apps']
 paging = True
 
 # search-url