Added help text to RTD location field

[snipe]

This just adds some help text to describe the Default Location to prevent confusion.

[what-the-diff]

PR Summary

• Introduction of a new language entry
  A new entry named 'rtd_location_help' has been added to the 'general.php' language file. It's used to provide contextual information or feedback to users in their preferred language.

• Adding a help text parameter
  The 'edit.blade.php' view file now includes a 'help_text' parameter to the 'location-select' form. This change makes it possible to provide explanatory text for the operation of the form's location selection, enhancing user understanding and use.