Fix up some group leader apis

api/PromoteToAssistant.lua

@@ -1,7 +1,7 @@
 ---@diagnostic disable: missing-return, lowercase-global
 
 ---@param unit string 
----@param name string 
----@param exactMatch boolean 
 ---Promotes a raid member to raid assistant
+---@overload fun(name: string, exactMatch: boolean)
+---@overload fun(unit: string)
 function PromoteToAssistant(unit, name, exactMatch) end

api/UnitIsGroupLeader.lua

@@ -1,7 +1,7 @@
 ---@diagnostic disable: missing-return, lowercase-global
 
 ---@param unit string 
----@param name string 
----@return bool leader 
+---@return boolean leader 
 ---Returns whether a unit is the raid leader.
+---@overload fun(name: string)
 function UnitIsGroupLeader(unit, name) end