README: Add FAQ entry on GeoClue access denied

README.md

@@ -25,7 +25,9 @@ FAQ
 
 **How do I install Redshift?**
 
-Use the packages provided by your distribution, e.g. for Ubuntu: `apt-get install redshift` or `apt-get install redshift-gtk`. For developers, please see _Building from source_ and _Latest builds from master branch_ below.
+Use the packages provided by your distribution, e.g. for Ubuntu:
+`apt-get install redshift` or `apt-get install redshift-gtk`. For developers,
+please see _Building from source_ and _Latest builds from master branch_ below.
 
 **How do I setup a configuration file?**
 
@@ -48,6 +50,18 @@ example clicking anywhere on Google Maps will bring up a box with the
 coordinates. Remember that longitudes in the western hemisphere (e.g. the
 Americas) must be provided to Redshift as negative numbers.
 
+**Why does GeoClue fail with access denied error?**
+
+It is possible that the location services have been disabled completely. The
+check for this case varies by desktop environment. For example, in GNOME the
+location services can be toggled in Settings > Privacy > Location Services.
+
+If this is not the case, it is possible that Redshift has been improperly
+installed or not been given the required permissions to obtain location
+updates from a system administrator. See
+https://github.com/jonls/redshift/issues/318 for further discussion on this
+issue.
+
 **Why doesn't Redshift work on my Chromebook/Raspberry Pi?**
 
 Certain video drivers do not support adjustable gamma ramps. In some cases