Revert inadvertent modification of type_reference/offapi.idl

...from 9835bb56 "MM: export the SwDocShell mail
merge via UNO."  It shall only be edited manually when deliberately going
incompatible.

Change-Id: I19c82dca3b6537631a155629d6072b516b32ded5

offapi/type_reference/offapi.idl

@@ -14535,7 +14535,6 @@ module com {
      const short FILE = 2;
      const short MAIL = 3;
      const short PRINTER = 1;
-     const short SHELL = 4;
     };
     published service NumberingLevel {
      [property] short Adjust;