Modify allow_gps_summary string (#1608)

Author: misaochan

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

@@ -102,7 +102,7 @@
   <string name="preference_license">Default License</string>
   <string name="use_previous">Use previous title/description</string>
   <string name="allow_gps">Automatically get current location</string>
-  <string name="allow_gps_summary">Retrieve current location to offer category suggestions if image is not geotagged</string>
+  <string name="allow_gps_summary">Retrieves current location if image is not geotagged, and geotags image with it. Warning: This will reveal your current location.</string>
   <string name="preference_theme">Night mode</string>
   <string name="preference_theme_summary">Use dark theme</string>
   <string name="license_name_cc_by_sa_four"> Attribution-ShareAlike 4.0</string>