Merge branch 'objectisinstance(lockable)' into 'master'

Doc: Add objectisinstance to lockable

See merge request OpenMW/openmw!4175

files/lua_api/openmw/types.lua

@@ -1538,6 +1538,12 @@
 --- @{#Lockable} functions
 -- @field [parent=#types] #Lockable Lockable
 
+---
+-- Whether the object is a Lockable.
+-- @function [parent=#Lockable] objectIsInstance
+-- @param openmw.core#GameObject object
+-- @return #boolean
+
 ---
 -- Returns the key record of a lockable object(door, container)
 -- @function [parent=#Lockable] getKeyRecord