Cache path description

PR for #14649
Correctlly describe the newly exposed cache_path field

administrator/language/en-GB/en-GB.com_config.ini

@@ -43,7 +43,7 @@ COM_CONFIG_FIELD_CACHE_PLATFORMPREFIX_LABEL="Platform Specific Caching"
 COM_CONFIG_FIELD_CACHE_PLATFORMPREFIX_DESC="Enable or disable platform specific caching. Enable when HTML output on mobile differs from other devices. (Default disabled.)"
 COM_CONFIG_FIELD_CACHE_LABEL="System Cache"
 COM_CONFIG_FIELD_CACHE_DESC="Enable or disable caching and set caching level. Conservative level: smaller system cache, Progressive level (default): faster, bigger system cache, includes module renderers cache. Not appropriate for extremely large sites."
-COM_CONFIG_FIELD_CACHE_PATH_DESC="Please specify a folder to store cache files."
+COM_CONFIG_FIELD_CACHE_PATH_DESC="Please specify a writable folder to store cache files if you do not wish to use the default folder."
 COM_CONFIG_FIELD_CACHE_PATH_LABEL="Path to Cache Folder"
 COM_CONFIG_FIELD_CACHE_TIME_DESC="The maximum length of time in minutes for a cache file to be stored before it is refreshed."
 COM_CONFIG_FIELD_CACHE_TIME_LABEL="Cache Time"