Make BT-113 optional

Currently, in the annex, BT-113 is conditionally mandatory for subtype 16 and 18:

This should be changed to optional for these subtypes.

Reason: According to ANNEX V, Part C, 10(a) of Directive 2014/24, in an FA, the information on the proposed maximum number of EOs to participate is to be included in the contract notices only “where appropriate”.