MDL-67593 core_iplookup: update lang string describing download process

Let users know they need to register on maxmind before granted download
access.

lang/en/admin.php

@@ -250,7 +250,7 @@
 $string['configfullnamedisplay'] = 'This defines how names are shown when they are displayed in full. The default value, "language", leaves it to the string "fullnamedisplay" in the current language pack to decide. Some languages have different name display conventions.
 
 For most mono-lingual sites the most efficient setting is "firstname lastname", but you may choose to hide surnames altogether. Placeholders that can be used are: firstname, lastname, firstnamephonetic, lastnamephonetic, middlename, and alternatename.';
-$string['configgeoipfile'] = 'Location of GeoLite2 City binary data file. This file is not part of Moodle distribution and must be obtained separately from <a href="https://www.maxmind.com/">MaxMind</a>. You can either buy a commercial version or use the free version. Simply download <a href="https://geolite.maxmind.com/download/geoip/database/GeoLite2-City.mmdb.gz" >https://geolite.maxmind.com/download/geoip/database/GeoLite2-City.mmdb.gz</a> and extract it into "{$a}" directory on your server.';
+$string['configgeoipfile'] = 'Location of GeoLite2 City binary data file. This file is not part of Moodle distribution and must be obtained separately from <a href="https://www.maxmind.com/">MaxMind</a>. You can either buy a commercial version or use the free version. You\'ll need to register to download the City database file, which you can do at <a href="https://dev.maxmind.com/geoip/geoip2/geolite2/" >https://dev.maxmind.com/geoip/geoip2/geolite2/</a>. Once you\'ve registered and downloaded the file, extract it into "{$a}" directory on your server.';
 $string['configgetremoteaddrconf'] = 'If your server is behind a reverse proxy, you can use this setting to specify which HTTP headers can be trusted to contain the remote IP address. The headers are read in order, using the first one that is available.';
 $string['configgradebookroles'] = 'This setting allows you to control who appears on the gradebook.  Users need to have at least one of these roles in a course to be shown in the gradebook for that course.';
 $string['configgradeexport'] = 'Choose which gradebook export formats are your primary methods for exporting grades.  Chosen plugins will then set and use a "last exported" field for every grade.  For example, this might result in exported records being identified as being "new" or "updated".  If you are not sure about this then leave everything unchecked.';