Open 'Dynamic_Localized_Strings' and look for

",
"AUTOTOOLTIP-npc_tractorbeam.odf", "
       Lock on a friendly or neutral target
         with disabled engines to get it towed.
         If a damaged wrackage is under your
         control and is being towed near a yard,
         you may issue a repair order to dock

     Weapon range: Dogfight
",

add beneath it:

",
"AUTOTOOLTIP-all_mining.odf", "
    Shot Delay
         Weapon range: Dogfight

       Locks onto a nearby Dilithium or Tritanium
         moon and transports the resources directly
         into the freighters Cargo hold
       The Dominion can also mine Supply in addition
         to the regular mining options
",