searchfilters: add to strings.xml 'content filter', 'sort filter' and 'filter'

Author: evermind-zz

app/src/main/res/values/strings.xml

@@ -15,6 +15,7 @@
     <string name="download">Download</string>
     <string name="controls_download_desc">Download stream file</string>
     <string name="search">Search</string>
+    <string name="filter">Filter</string>
     <string name="settings">Settings</string>
     <string name="did_you_mean">Did you mean \"%1$s\"?</string>
     <string name="search_showing_result_for">Showing results for: %s</string>
@@ -755,4 +756,6 @@
     <string name="feed_toggle_show_future_items">Show future items</string>
     <string name="feed_toggle_hide_future_items">Hide future items</string>
     <string name="sort">Sort</string>
-</resources>
+    <string name="filter_search_sort_filters">Sort filters</string>
+    <string name="filter_search_content_filters">Content filters</string>
+</resources>