oleaut32: Implement ICreateTypeInfo::SetVarDocString.

dlls/oleaut32/typelib.c

@@ -9196,8 +9196,19 @@ static HRESULT WINAPI ICreateTypeInfo2_fnSetVarDocString(ICreateTypeInfo2 *iface
         UINT index, LPOLESTR docString)
 {
     ITypeInfoImpl *This = info_impl_from_ICreateTypeInfo2(iface);
-    FIXME("%p %u %s - stub\n", This, index, wine_dbgstr_w(docString));
-    return E_NOTIMPL;
+    TLBVarDesc *var_desc = &This->vardescs[index];
+
+    TRACE("%p %u %s\n", This, index, wine_dbgstr_w(docString));
+
+    if(!docString)
+        return E_INVALIDARG;
+
+    if(index >= This->cVars)
+        return TYPE_E_ELEMENTNOTFOUND;
+
+    var_desc->HelpString = TLB_append_str(&This->pTypeLib->string_list, docString);
+
+    return S_OK;
 }
 
 static HRESULT WINAPI ICreateTypeInfo2_fnSetFuncHelpContext(ICreateTypeInfo2 *iface,